Does Apple Watch works in Pakistan?

If your iPhone works, then you can use a GPS only Apple Watch model, as that just depends on your iPhone for radios when away from WiFi.

What the Apple Watch GPS-only can do without an iPhone

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

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

Not at this time. Here is where the watch is available....https://www.apple.com/watch/cellular/