Never used a HRM riding, but can feel the heart pounding and I’ve counted 4 a second sometimes, so that’s 240.
It’s all very individual and not that fitness related as I understand it. Some will naturally have a high rate, some not.
What is more important is the speed it goes down at rest. Not just when you get home, but when you stop on a ride. It’ll still be higher than normal, but should go down significantly given 5 or 10 minutes. Mine used to stay high for ages and also would be at about 80 at home for almost half a day after! With fitness just through riding a lot it comes down quicker and is more around normal at home.
Though had a couple of freaky moments at home recently when I realised it was going very slow. Got the BP monitor out and was down at 40! Soon went back to 50 to 60 which is my normal at home. BP by the way is kept in the normal zone thanks to riding. Used to be borderline nearly into the high zone before (going by NHS levels. In US they’d have you on drugs way in advance of that).