It would be nice to have two rifles - one he can enjoy shooting and practicing with, like a 223, and a larger hunting rifle.
Too many people think they have to tough it out and enjoy plinking with a big caliber in order to take it hunting, but that’s just not true. I enjoy heavy recoiling hunting rifles, but outside of the season a 243 is what I’m normally plinking with.
In Jr high school I couldn’t wait to get a 270 - I didn’t want anything else. It was perfect for hunting but recoil is noticeable. I ended up borrowing a 243 for plinking/varmints so often that it became a favorite - recoil is half of the 270 - had it been available to me, a 223 would have been just as good and cheaper.
At least in our family there is a loaner 243 that almost all new hunters have used for deer and antelope, then they usually upgrade to a larger caliber as they get older, but there are plenty of adults that still go for the 243.
Recoil tolerance is very individualistic - and seems to depend a lot on how older shooters talk about it. I always have a shoulder cushion of some kind that can be used if they want so it physically doesn’t hurt, and good ear plugs and muffs. A lot of praise for hitting things takes their mind off recoil, compared to adults telling the young shooter that it’s going to kick like a mule or beat the heck out of them. Recoil was never mentioned around my 5’2” first wife - she started out taking an antelope at 450 yards with 243, then shooting my 7 mag didn’t bother her so I bought another 7 mag and cut the stock down for her and she was deadly with it.
Getting used to shooting standing up or leaning over the hood of a pickup makes recoil much less bothersome. Now I have a tall tripod and cushioned bag that can be used as a standing rest for the same reason. Everybody wants to shoot prone, but that’s not fun - wasn’t when I was 12 & isn’t now.