I don't think it's possible to change a player's gamer tag on a server with Skript/ However, you could probably change a player's display name (The way it shows up in chat/tab) and you could also maybe have their skin changed too.
#change player's nametag or use a skript variable as a papi placeholder
fallen herald
fallen herald
Yeah, I believe that is possible
fallen herald
I think so. You could probably do something like:
set player's displayname to "Example". You'd have to insert your code before this line though for like if a player gets a bounty put on them and also to account for the player's usual display name + the icon.