Depending on where, and what you’re fishing for, I would avoid a reel at the age of 5. my son is similar age, he uses a cheap 3m whip, which is easier for him to control on his own and catch small fish with. At 5 or 10 quid, not the end of the world if it breaks either (though they might think so).
I have tried him with a feel, I bought a tiny penn captiva in, I think, a 1000 size but it might of been 2000. It’s tiny. They don’t have anti reverse, but do have a good drag and you’ll find he’ll reel whatever, whether the fish is big or small, so I don’t think the lack of anti reverse hurts. they’re front drag, and burly metal constuction. Got mine from poingdestres when I was on holiday, and teamed it with a 6ft spinning rod, but to be honest it’s proved too complicated for him so far, so we use the whip instead.