Will apple watch series 5 with cellular work on the Tracfone network?

You mention an Apple Watch Series 5 with cellular in the Question area, but in the explanation, you mention without cellular. While Tracfone is not one of the supported carriers, if you pair the GPS only watch with the iPhone, you will be able to make calls with the watch as long as you have the iPhone nearby. You would not be able to activate a cellular watch on the Tracfone network.

ChrisJ4203 makes an excellent point, and it is something I should have noticed.

A GPS only Apple Watch does not care what your iPhone cellular carrier is. A GPS Apple Watch will work anywhere your iPhone works.

A GPS only Apple Watch can do Everything the cellular model can do as long as your iPhone is nearby, and you iPhone's carrier has nothing to say about it.

What the Apple Watch GPS-only can do without an iPhone (there is information about the cellular model as well)

https://support.apple.com/en-us/HT205547

https://www.imore.com/heres-what-apple-watch-can-do-without-iphone

Cellular Carriers that support the Apple Watch, which models, the radio frequencies each model uses, and the country where they offer service:

https://www.apple.com/watch/cellular