We have a few DC primary school/pre-school age. Whenever it’s their birthdays, I always have a cake made (as I can’t bake!), get them a balloon stack/a helium balloon, put up some banners, blow some balloons up, birthday badge etc. Everything usually goes with a theme of something that they’re into at the time.
And I do the same for DHs birthday too (more for the kids benefit than his - they enjoy doing all of this).
DC’s get a class birthday party plus a family birthday tea at the house.
Dh always rolls his eyes slightly at all of this (although he’s never said anything). He comes from a family where you’d be lucky to even get a birthday card so thinks I’m OTT with this sort of stuff. I’ve explained that this is completely normal before, but he still thinks I’m OTT!