According to the Poser 13 Win/Mac specs at https://www.renderosity.com/marketplace/products/159003/poser-13-windows-and-mac, P13 requires at least macOS 12 (Monterey) with 8 GB system RAM. With that configuration or better, Poser 13 should run for you. No guarantees, of course.

Personally, I'm sticking with High Sierra 10.13 and P11 Pro, since I'd lose too much irreplaceable legacy software I depend upon daily by going higher than 10.13, thanks to Apple's obsoleting more and more stuff with every new OS "upgrade." No wonder Poser's developers have given up on trying to keep up, especially since (I suspect) we Mac users are a niche market for them.