Crucibelle and Crucibelle-M were made to explore the generational gimmick in a special project that would design two similar Pokemon at the same time. It's best to view it, I think, more akin to Venomicon and Venomicon-E. The key difference between then and now, of course, is that Megas were allowed in OU and CAP play, while Dynamax and Gigantimax are banned. Because of the ban, I would consider it very, very unlikely CAP sets out to design a Gigantimax form for a Pokemon, even if it would only be flavour at the end of the day.
However, that hasn't stopped artists from doing renditions of what Gigantimax forms of CAP Pokemon could look like. You can see the gallery of some of those
here.