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.
Moshi Overture for iPhone 6 Plus is retailing for S$59.90. There are three colors available, Brushed Titanium to match your gold iPhone, Sahara Beige to match your silver iPhone and Steel Black to match your space grey iPhone.
If you are using iPhone 6, the same choices of colors are available and it is retailing slightly cheaper at S$54.90.