apple watch series 3 gps+cellular

Apple’s list of supporting networks Apple Watch - Carriers - Apple does not show any service in Philippines.

You can use the cellular model, but it would work like the GPS non cellular version, making all its communication through your iPhone. For this reason it is pointless to spend the extra money for the cellular model, but if you already have one purchased outside Philippines you could continue to use it.

Read the following to help clarify what you can do with the GPS only model vs the Cellular (mostly everything if you keep your iPhone nearby)

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