Can I dive using a 200M water resistant watch?

Sure, you could dive and make it, but watch might not.
Water-resistant is not the same as waterproof.
But why not? Go for it.

How deep and how long? The words "water resistant" are NOT the same as "water proof" fyi.
A 200m watch will probably do fine at depths to 30ft (10m) for long periods of time.  Since most of us recreational divers dive 60ft to 90ft during a typical day, I wouldn't count on that watch surviving for many days.

For that matter, why would you need to wear it while diving?  It's not much of a fashion show at bottom, nor on the boat before or after diving.  You or someone with you will undoubtedly have a dive computer with the time.  There is no valid reason to wear it during dives.  Save it for the pool.

here's a link that might help
https://waterproofsmartwatches.com/what-does-200m-water-resistant-mean/

Do you know diving?

I got a watch many years ago that claimed a certain depth of water resist, and it died in an ordinary rain shower.  Perhaps there are now rigorous legal standards for such claims, I don't know.  Or it could be like the capacity of NiMH batteries, stamp whatever they want, and let the buyer beware.

If you have a specific brand and model in mind, the divers on this board could probably advise.

A "200m" rater water resistant watch is OK for normal scuba diving to a maximum of 50m.

The pressures due to movement in water are rather higher than the static pressure at whatever depth, so you should never assume a depth rating on a watch to be a practical value. A 5m rated watch can leak water in a 2m deep pool..

(Whether you can dive is something only you know).

Depends on how deep you're going. 200m doesn't actually mean they've taken the watch down that far to see if it holds up. 200m watrer resistance pretty much means suitable for professional marine activity, serious surface water sports and skin diving.

Yes, if it's rated for that depth you can use it for scuba diving.