Yes, a plastic "snap on" clear (top) case off Amazon on my Apple watches, always, 100% of the time.
But I do not baby the watch; I do not take it off for any reason (other than sleep). Change oil on my car? Have the car on the lift and work on brakes? Build something in my garden? Rock climbing? Watch is always on my wrist.
It is the last activity (rock climbing) where I damage / crack the case most often. It does not happen as often as it used to but it does happen (falls are not exactly graceful). And I replaced cracked cases multiple times.
The size difference with the case is (IMO) not dramatic (but is noticeable when you start). My 42mm S10 + the case is still smaller than the Ultra or the 46mm watch.
Might not be right for everyone but it is definitely right for me.