When I was buying my E I also enquired about this. I think it would depend on the dealer, but the first one I asked (general used car dealer) would not do anything - acted as if plugging something into the OBD port might damage the car

. That said I don't think there's any harm in asking and you should ask.
After my experience I didn't ask, but I did try to select the car carefully where I felt it was fine not to ask, i.e. low mileage, but not too low as this would mean the EV might have been left to discharge and sit discharged, and looking at the trip computer miles/kWh across the full mileage of the car on the dash, and the miles/kWh obtained from a recent trip or test drives under different types of condition/driving. The car should also store its average speed through it's full mileage on the dash unless that has been cleared, mine was about 11 mph for 3000 miles, indicating normal stop/start city driving.
There are several ways to get some sort of check of the battery state of health if the dealer agrees:
1. They can use their own diagnostic readers
2. There is an app called Power Check Control on Android/iOS which together with a compatible OBD reader can read it.
3. Car Scanner app also does the same.
But the problem with all this is that you don't know what the state of health was when the car was new, it's not necessarily 100% at new. And even if you do, you don't know how the car's black box BMS generates this number, or whether it's reliable, or what it really means in practice until you start observing measurable differences in your own driven range/efficiency. Maybe the SoH was 92% new, but now after 18,000 miles it's 90%. Maybe a car that has been cycled in the most optimal way has 93% after all that mileage. Who knows.
Secondly, I also don't think the SoH would tell you much about how the car was charged, how often it was fully discharged, or whether it was rapid charged all the time (more wear on the battery, and more likely with higher mileage but not quantifiable) or slow charged, and I don't think the car keeps a history of this, at least not in any way that is accessible to the user.
I suppose my point is that you're probably better off not worrying too much about this, and if you are worried, then choose a car with low-decent mileage, I think 18,000 is in that range but maybe under 10,000 would be better so it doesn't bother you. That's what I did, that said I also believe the batteries in modern EVs are really robust, and it should take really abnormal usage over long periods of time to have any detectable impact on their ability to retain a charge, conditions that you're unlikely to see on a small range/slow charge predominantly city car like the E.
Lastly, make sure the car has full service history, it sound stupid but in the 0.00001% chance the car becomes a brick it's not clear to me whether Honda will honour the separate 8 year warranty on the HV battery if it does not.