My daughter and her fiance met on OK Cupid, several years ago. A professional matchmaker couldn’t have come up with a better pairing. Uncanny. Prior to that, she was on Tinder, but found it too hook-up oriented, tough to wade through the lame options. But she did date 2 great guys she found there, one of whom is still a friend. They had a lot of plain old fun together.
Maybe your son’s issue is the small dating pool in his rural county. Can he expand his search radius? I know so many people who matched online, of all ages. We had a thread here about adult posters who found their partners that way, not as young’uns (eg, post divorce.)
Agree about ideas like MeetUp. But what’s available also depends on where you are. In some areas, biking groups are a great idea, casual cyclists seem to be a very friendly group. Hiking gets people talking to each other. Committee work is a good opportunity, if the right others are there.