I'm planning on making a Mind-flayer character for D&D 5e and need their traits. I need to know special abilities, stat modifiers, and other things needed for character creation. A site that provides this would also be useful.
There are no official stats for mind flayers as player characters, for what are probably obvious reasons. However, if your DM is on-board with this character concept, have them create the race's PC stats/traits using the rules in the DMG on pages 285–7.
If your DM is not on-board with the idea of an illithid PC, you're out of luck — for custom things like new races, the DM's decision generally stands.