The New Mutants cut Warlock from the screenplay when Fox decided to slash the movie's budget, but planned reshoots were supposed to add him to the movie. That didn't happen thanks to the Disney/Fox merger, of course, but we do now have some idea of what he might have looked like!
Concept artist Deryl Braun has shared some of his early designs for Warlock and, as you can see, it definitely appears as if the plan was for him to look almost exactly like his comic book counterpart.
Sacha Baron Cohen was director Josh Boone's top choice to take on the role of Warlock in The New Mutants, and leaks from earlier versions of the screenplay revealed that the plan was for him to be a sentient computer programme Professor X had discovered (that likely would have changed once it became clear Mister Sinister was pulling the strings from the shadows).
It's probably going to be a long time before we get to see the New Mutants characters return to the big screen in the Marvel Cinematic Universe, but these designs being taken into account when/if Warlock does eventually make his live-action debut would no doubt be welcomed by many fans.
Check out the concept art below: