I am personally a fan of the chao garden from the Sonic Adventure games and so i've compiled all the links you will likely want or need to play Sonic Adventure 2 on PC. most mods are just to make the game feel slightly smoother or make the story make more sense in english.
the biggest actual overhauls are two mods for the chao garden which greatly expand upon it. there are obviously more mods that one could install, but i tried to keep it to essentials.
--This is the Mod Manager itself. For booting the game with mods. it says it's for Sonic Adventure DX, but it is for BOTH Sonic Adventure games--
https://gamebanana.com/tools/15436
--Render fixes, for the fact that these games were very poorly ported to PC--
https://gamebanana.com/mods/452445
--Controller Input Smoothing (you want this)--
https://gamebanana.com/mods/515637
--SDL mod; pairs with Input Smoothing--
https://gamebanana.com/mods/615843
https://gamebanana.com/mods/381193
--Story Retranslation (use japanese voices + english subtitles on; the subtitles will now give you an accurate telling of the story. the official english translation is awkward and makes less sense)--
https://gamebanana.com/mods/437858
--Hint Retranslations, for treasure-hunt levels--
https://gamebanana.com/mods/350607
--Level Bugs and Oddity Fixes--
https://gamebanana.com/mods/48894
--Chao World Extended (currently V9.6) WORTH READING THE MOD PAGE IN ITS ENTIRETY--
https://gamebanana.com/mods/48840
--Enhanced Chao World (less frequently updated but can operate alongside Chao World Extended) ALSO WORTH READING MOD PAGE--
https://gamebanana.com/mods/48915
--Chao Eye Fix (their eyes are kinda messed up sometimes lol)--
https://gamebanana.com/mods/9114