servers i know:
art fight- https://discordapp.com/invite/GrDHvte
is the yearly art figth discord server,it's mostly there to organize the event but you can post art,adopts and play art minigames all year long so I add it to the list,this group is SFW.
minigames and art trades-https://discord.gg/pJBkNGX
a discord server where we host minigames and you can ask for people to make art trades with you, you can also post your art or ocs there!this server is SFW