So, I had a little fun last night and tried to imagine ways to implement "Homebrew options" to the game.
1) Have those options available when starting a new game. This could be the same menu that allows player to change/custom the difficulty settings.
2) Have those options available in the "Options" menu, under "User options" with "Weighted dice". Or, in the CC if it's relevant there (Racial abilities score from TCoE for example).
Indeed, DOS2 implemented "Giftbags" the players could enable in the game. Those were mostly
popular mods officially added to the game, apparently (pretty dope). They could do the same here.
Although, I'm not sure it's necessary to lock achievements for most of them (like in DOS2). Only the one that would "break" the game maybe?