The last time Apple produced a folio case for the iPhone was for the iPhone 11. My mom loves folio cases. Sadly, for iPhone 13, Apple stops producing it. So the only way to get a folio case is from a third-party accessories maker like Moshi.
I got the Moshi Overture Case with Detachable Magnetic Wallet For iPhone 13 Pro that retails for S$77 for my mom. It comes in two colors, Black and Pink. I chose pink.