need tips with ending a huge 6 month long arc in a dnd campaign

[Salgood]

a while ago i stared being way more serious dming for a campaign im running and have been regularly playing with my players a lot more often and at the beginning of me getting more serious a huge mission was started by the party to prevent a world ending event and return a powerful unconscious being to its owners. Since then the party has learned a lot more about the world and I've put a lot into expanding the factions and countries in the world and I've set up a lot for future events but now im needing tips on wrapping up this arc and getting ready for future missions the party may go on. Any advice would be wonderful and really appreciated thanks in advance :).

[Beni-Kujaku]

I guess "end it with a bang, make your players feel like they're strong or have become stronger, then tease the next arc with an event that makes your players feel like they still have a lot to learn and can become much stronger" is the best I can give without knowing your player's level, how long the rest of the campaign is supposed to be and if there's even a last obstacle to overcome before ending this arc. But yeah, ending a McGuffin arc by activating the McGuffin (in your case, having the being waking up) always makes for a strong bridge into the next.

[RNightstalker]

Hopefully you know what the players want to do with their characters. I would say leave an easter egg that sets the characters onto completing their goals. Tease a castle that's owner just died because one character wants to own a castle; the player looking for an artifact finds a map or hears a nugget to get them on the trail; etc. Don't be afraid for the BBEG to escape to come back again.

[Kol Korran]

It is very hard to help, if we don't know more of the specifics:
# Who are the players? What have they found especially engaging, what drew their emotional response and involvement?

# Who are the PCs? What is important to them? What (people, places, undertakins, other stakes) are they invested in?

# What is the world ending event? Who are the powers/ factions/ beings involved in this conflict? What are their main goals, resources, plans? How have the PCs interacted with these powers so far?

# Who/ what is the powerful unconscious being? Who is he being returned to? Again- the same questions as above apply to these as well?

# Do you have any specific special preference as a DM? Level of complexity?, Lethality? Things you'd love to include? Things you want to exclude? Other restraints? (Such as time, resources and such)

Try and tell us as much as you can on the above, and we can try and help you.

[Salgood]

It is very hard to help, if we don't know more of the specifics:
# Who are the players? What have they found especially engaging, what drew their emotional response and involvement?

# Who are the PCs? What is important to them? What (people, places, undertakins, other stakes) are they invested in?

# What is the world ending event? Who are the powers/ factions/ beings involved in this conflict? What are their main goals, resources, plans? How have the PCs interacted with these powers so far?

# Who/ what is the powerful unconscious being? Who is he being returned to? Again- the same questions as above apply to these as well?

# Do you have any specific special preference as a DM? Level of complexity?, Lethality? Things you'd love to include? Things you want to exclude? Other restraints? (Such as time, resources and such)

Try and tell us as much as you can on the above, and we can try and help you.

the players are all family members of mine irl and the setting is set right before the 19th century in our world with a lot of changes such as Britain being a country that is controlled part by government and part by religious pantheons and that is currently undergoing a power switch with many pantheons uniting to overthrow the government, America is under control of the Pinkertons using fear mongering to silence the general population from discussing anything wrong going on in the world (think there is no war in ba sing se type thing) and Greenland, Ireland, and Scotland are all under the control of the fey and more specifically the seelie court and queen titania, titania tried many years ago to destroy the governments in all major countries a few hundred years ago but now has a curse on her that stops her from claiming any or "freeing" any country she now is finding a way to continue her liberation of countries through a loop hole however the party does not know this yet. there's also many Lovecraftian roots such as the monster there trying to return to a museum being a great old one that if woken up starts the cycle of all elder gods awakening. for a short description of each of there characters one is a gunslinger who was a former Pinkerton when his father who he worked on a Pinkerton party with along with the rest of his past party died in an attack that he got out of and is now looking to solve who did it. another is a monk that was a paladin in the past and changed after his church where his grandpa was the leader of was destroyed. another is a mortician sorcerer who in all honesty doesn't have any backstory and hasn't been a large part of the campaign from not getting involved in roleplay and story even when I've made stuff specifically for her character if u had any advice in getting her interested somehow that would largely be appreciated. Another is a wizard who has mainly been guided by a spirit that's following him that is trying to corrupt him with a sword that was used to end a war between elder gods and great old ones by the elder gods but has great old ones magic on it that causes corruption. and the last is a rouge spy like guy that is very into researching all the occult parts of the world and solving some of the mysteries. the church of loki who started the coup with all the pantheons in england are the ones who stole the sleeping great old one to awaken it and are also the ones that destroyed the monks church. For some more characters in the story theres the president of the US who unknown to the party killed the father of the monk a long time ago when he was a child to gain power from a devil lord and ordered the murder of the former Pinkerton gunslingers party and father, anderson murphy a illithid pirate the party is friends with and queen mab the unseelie courts queen who is insane after having her mind destroyed by her sister titania although none of that is known to the party. Im so sorry with how much im writing btw im trying to give as good a picture of everything up to this point that ive written and im having difficulty keeping it brief but the last thing to say with my personal preferences is i dont mind complexity infact id love as complex as possible to keep the party busy with many mysteries as they seem to be enjoying it time and resources shouldent be an issue i dont think and although i usually like to make all fights in favor of the party usually to avoid death with a huge fight around the corner i wouldent mind boosting the challenge but just for some warning the gunslinger is incredibly op and can be hard to find a good balance with lol. Thank you so much in advance if nothing else i atleast can look back at this as a cheat sheet recap of the big story stuff :).