They will be fine but it's way too much land for two sheep. "Average" stocking rates are 5 ewes and lambs to the acre, depending on how good the grass is, the season, the type of ewe etc etc so if all you are going to do is keep two sheep on it, it's a bit of a waste.
Also if you let them have 10 acres, they will graze selectively, they won't keep the grass down and they'll poop all over. Probably better to make a small paddock or two to keep them contained.