Auto Lock when Folio Case Cover is Closed

I just upgraded from iPhone X to iPhone 13. With the X, I had an Apple leather folio case, and when I closed the cover, the screen shut off and the phone locked. I was disappointed that Apple didn't offer a similar case for 13. I am so used to having it that I sought one out from Nomad. It's fine, except that I'm annoyed that the phone does not lock when I close the cover.

Any ideas as to why it's not locking automatically? Was it unique to the Apple case or the iPhone X? Or, is there a setting somewhere that I haven't found that will enable this automatic locking when the cover is closed?

Thanks

iOS 15.1