But that's not 2x the size evenly, so I don't think that would be worthwhile. That's an advantage of the hexagonal shape that JWST used so that it could unfold to increase the size evenly.
With its 9m fairing Starship could nearly double JWST's collector area with no folds.
Big rockets solve a lot of problems.
Or, put a JWST 2.0 with hexagonal segments each the size of the full JWST diameter, and fold that up into Starship... Yes please!