Belt of Giant Strength provides a high strength bonus. PAM+Haste+Extra Attack provides 4 attacks. Smite + Improved Smite adds dice to everything. GWF raises the average of all damage dice (with RAW version, rather than twitter version). GWM matters occasionally (but is mostly there for your sustained damage, not your burst). Advantage from the Channel Divinity setup or the mounted bonus or other possible sources. Should be ~150-200 depending on what grade of Giant's Belt you're using. Can do more if you can get a reaction attack (from either PAM or Soul of Vengeance or OA), magic weapon, ally buffs, or have your steed attacking.
It's not the highest nova DPR in the world, but it's very good for a straight-class Paladin, and Paladins bring lots of other goodies to the table besides just their DPR (such as a very fast and durable steed, or a 30 foot +5 saves aura).
You also have solid sustained DPR too. Your easy access to Advantage, GWM, 3 attacks (plus possible reaction attack), and long-lasting buffs like Hunter's Mark or Holy Weapon mean that you can instead opt to stretch out your resources while dealing solid damage and only smiting opportunistically (such as on crits).