How to downgrade iOS version?

For a work project i need a ios version 16 or under, and my phone updated to ios 17. This was a while ago but internet didn't help much to find a way to get the iphone back to ios 16. Does anyone here know a way to do it? It's an iphone 13 if it matters. Thank you for your time.

Just to clarify, the reason is compatibility of several softwares used for the project iOS 17 is not compatible.