Start with how far into it he is
"Plays golf" covers a lot of ground for a son, from the one who took it up last summer to the one who's been chasing a lower handicap for years, and they want opposite things. The occasional player wants gifts that make a casual round more pleasant - a decent glove, a towel, sunglasses. The keen improver wants tour-level balls, a distance tool, or something that helps him practice. Buying up to the wrong one is the easy miss.
Improvement gifts land well with a keen son
A son who's genuinely into golf usually wants to get better, which opens a category that doesn't work for everyone: practice aids. A putting trainer he can use on the carpet, a set of alignment sticks, or a swing trainer are all things a motivated golfer uses and rarely buys himself. The honest caveat is that these only land if he actually wants to practice - for a purely social golfer they gather dust, so read the room first.
The big gift that isn't fitted
If you want one substantial gift, a rangefinder is the standout, because unlike clubs it isn't fitted to him and a keen younger golfer often hasn't bought one yet. It gets used every round and it's the sort of thing that quietly helps him play better by taking the guesswork out of distances. Just confirm he doesn't already own one - the bag-pouch check applies here too.
Consumables never miss
When in doubt, a dozen premium balls in a brand he recognizes is the safe, always-welcome gift for a son at any level. It's consumable, needs no size, and gives him more of a thing he rations. Pair it with a small accessory - a marker, a glove, a funny pair of socks - and it reads as a complete gift rather than a stocking filler.
What to leave to him
Clubs and a putter are fitted to his height, swing and hand, so buying them blind is a gamble even a parent shouldn't take - if the goal is new clubs, put the money toward a fitting he books himself. Shoes and apparel need a verified size and width. And off-brand balls are a false economy any golfer spots. For a spread across every budget, the golf gifts for men page covers more.