I would go with what he’s into. My son loves fire trucks and excavators. But we thought he liked fire trucks more so made that a theme and he was absolutely loving the decorations. Got upset we cut into his firetruck cake though, I guess he thought it was realistic enough to be a toy.
I did Two Fast theme because my son is really into cars
For our eldest who's two, he had duggee for his first birthday and paw patrol for his 2nd as that's what he was interested in. Our youngest will be 1 this week and for him as he loves animals we're having a farm theme and have organised for 2 baby goats to come for the kids to stroke Go with what they are interested in. Then save it all in a box incase you ever revisit the theme x
We did a "2 fast" theme, with lots of racing car decorations, he is a car lover and was born in Early January
My son is really into trucks and heavy equipment so we did a construction theme with a build your own taco bar. Is there something he's really into?