You can ask your doctor to order a tilt table test, that’s a pretty standard diagnostic test for POTS

No need for a tilt table! Most cardiologists will do a series of blood pressure testing while having u sit, lay down, and stand. Then they will do a heart monitor for 48 hrs to check for large spikes in rates.

I’m in the US I’m not sure where you are but my doctor mentioned a tilt table test but first I had to redo my echocardiogram and stress test. During the stress test he said my heart rate jumped so high when I first stood up that there wasn’t a need for the tilt table test. I might do it at some point but it’s not need now. They can pretty much tell without the tilt table test depending on how bad it it.