Will my Apple watch se work with an apple trachphone?

Apple Watch Ultra, Apple Watch Series 8, and Apple Watch SE (2nd generation) require an iPhone 8 or later with iOS 16 or later. For more info, see:

Apple Watch SE (2nd generation) - Technical Specifications

Any GPS only Apple Watch will work with a Tracfone. If you purchase a new Apple Watch, it MUST be paired with an iPhone running iOS 16 or higher (current version is 16.2), so your iPhone 7 is not compatible with any watch Apple sells currently.

No Apple Watch Cellular will work with Tracfone, because they do not support cellular services for Apple Watch. If you intend to stay with Tracfone, a GPS only watch would be the way to go. But if you think you'd like the advantages of having cellular service on an Apple Watch, you need to move to full service carrier, who does support Apple Watch.

This link lists the carriers who support Apple Watch --> Apple Watch - Carriers - Apple

Yes, it will. But you will need to use it as GPS only Apple Watch, even if you buy a cellular Apple Watch, unless you switch carriers to one who support Apple Watch. Your iPhone SE will need to updated to at least iOS 16.