Hi
Yes, you can.
Apple Watch Series 3 (GPS + Cellular) can be paired, set up and used for other features whilst skipping the steps to activate cellular. It will then function like a GPS-only model.
The built-in cellular feature can be enabled later in the US, if and when desired, subject to having a compatible service plan on your iPhone that specifically includes support for the Apple Watch, including the carrier activating the watch on the plan. Be sure to buy the correct model of Apple Watch for compatibility with US carriers:
In the meantime, it can be used in Qatar in conjunction a service plan for your iPhone (which must be an iPhone 6 or newer model, running the latest version of iOS) from any carrier.
Keep in mind also that, if buying Apple Watch in another country, warranty service availability in Qatar may be restricted.