Is IOS 16 Beta safe for download?

By definition, beta software is not finished and has bugs. While it isn't going to do damage to your hardware, it could damage data and cause you to spend time recovering. I concur with lkrupp on this.

Apple’s event is tomorrow 9/7/2022. The release of the actual iOS 16 is very near so my advice would be to wait a few days instead of installing the beta.