You cannot say for sure of course. My OTB is about 600 pts lower than my online rating, but that is probably on the high side. I don't think many people have better OTB ratings.
YOur OTB would probably be higher if you played more. I checked your stats and you have increased around 300 rating points in the last 90 days. However (I assume because of the coronavirus), you have not played any rated events and therefore your OTB has not had time to catch up.
With OTB you are going to take more time to calculate. Online you just click a mouse button or worse press a button on your mobile device.
There should be a more structured way to evaluate online vs. OTB other than relying on people playing in their pj's and undies while cooking, cleaning, parenting, working, doing schoolwork, etc....