will crash detection work on a 13 promax and a SE watch without cellular?

If your Apple Watch Series 8, Apple Watch Series 9, or Apple Watch SE (2nd Generation) detects a severe car crash, it can help connect you to emergency services and notify your emergency contacts.

If cellular and Wi-Fi coverage are not available, and your iPhone 14 or iPhone 14 Pro or later is near your Apple Watch, Crash Detection notifications to emergency services may be communicated by the Emergency SOS via satellite system, where Emergency SOS via satellite is available. See the Apple Support article Use Emergency SOS via satellite on your iPhone.

For more info, see:

Manage Crash Detection on Apple Watch - Apple Support

and the 'iPhone and Apple Watch models that work with Crash Detection' section in:

Use Crash Detection on iPhone or Apple Watch to call for help in an accident - Apple Support

1. The iPhone 13 will not detect the crash regardless of what iOS version it is running.
2. If the Apple Watch SE is a second generation or later it will detect the crash and attempt to place the call to emergency services itself. It may use the iPhone to place said call if necessary if it can't place the call itself and the iPhone is nearby and can place the call.