What if you offered the players a boon for submitting a suggestion that they're willing to tolerate? Like, an archer PC gets a bonus feat in exchange for a "strong winds" condition that sometimes penalizes his arrows?
One of my players has a warlock whose patron is basically the Phantom of the Opera. Her eldritch blasts - and chromatic orbs - look like musical notes and such, like in that one fight scene in Dr. Strange 2.
I was just thinking about this. You could also allow a character to counter a spell with a thematically-appropriate anti-spell - like blocking firebolt with ray of frost.
I wanted to play a warlock in a really low-level game whose Blade Pact was an evil butterknife. When play starts they've just managed to trade up to a letter opener.
I think this should be restricted to a game focused directly on arcane casters, where more involved spellcasting systems would be most needed. In a bog-standard D&D game it would be superfluous.
The last game I played (briefly) was fully rolled, 4d6 drop lowest. I proceeded to roll 6 stats 15 or above. I got permission from the DM to trade rolls with other players and share the wealth.
Back in 2nd ed I remember a player whose character had a 4 CON - because they wanted to play a Diviner and that's the way the stats had to be placed - and they had a lot of fun describing how the character had to stop for breath at the top of a staircase and such.
Considering that prosthetic limbs exist in core rules, but magical extra hands don't - yes, saying the artifice wing only replaces a real one is a legitimate call.
Way back in 2nd ed., I had the local would-be evil empire learn a way to turn their elite soldiers into gargoyles. The campaign started with the PCs supporting an army discovering that their enemy was (a) flying and (b) immune to normal weapons. The players were fine. The army was screwed.