The only Letters Patent for the title Prince of Wales I can find is one that was issued in 1958. When the late Queen created Charles Prince of Wales. I can no other. Truthfully I always thought that when the monarch announced that their heir as Prince of Wales, that was it.

https://www.rct.uk/collection/themes/exhibitions/hrh-the-prince-of-wales-an-exhibition-to-celebrate-his-sixtieth-birthday/windsor-castle-drawings-gallery/letters-patent-for-the-creation-of-charles-duke-of-cornwall-as-prince-of-wales-and-earl-of-chester