Questions about monsters and stats

[MintyThe1st]

I want to make some custom monsters but am unsure if the same rules apply as 3.5 when it comes to the stat block.

in 3.5, if a monmster has 18 Str you assume it has a racial bonus of +8 Str and a 10 assigned to Str. Is this still the case?

also, monsters are allowed to have up to 30 in a stat, does this also apply to monsters that dont naturaly have any stats above 20?

[Zman]

Give the monster creation rules in the DMG a read through, they'll help you out.

No, you can't just subtract 10 to get the racial bonus off an NPC statblock. Unlike 3.5, 5e monsters and NPCs aren't built the same way as PCs. It's far simpler, but far less supportive of monsters as pcs. LA is no longer a thing.

[MintyThe1st]

I wasn't trying to make monster characters, I want to make NPCs that are a cut above the typical member of their race. Like an Ogre chieftain or something along those lines.

[BurgerBeast]

The Angry GM has an awesome article about how to build monsters. I strongly recommend it. (Sorry, no link since I'm on my phone).

But generally, just pick the hp, AC, to hit, and damage stats you want the chief to have, and then calculate CR as usual. This gives the proficiency bonus (because it depends on CR), which you can use to determine the ability scores.

You might need to tweak here and there, but after a few tries, it gets very easy.

[Zman]

I wasn't trying to make monster characters, I want to make NPCs that are a cut above the typical member of their race. Like an Ogre chieftain or something along those lines.

Sure, take a look at my signature, in it are links. One of them is my MM Expansion, I have lots of examples of what you're looking for. I.e. An Orge, Ogre warrior, Ogre Shaman, Ogre chieftan, and Oni. Not just Ogre and Oni.

A good amount of stuff has been tweaked from stock, but most are close enough to give you the basics on how i built up from the base monster.