I would have offered, but checked. As in I'd expect to be serving up a meal, but texted the mum to check that they didn't plan to eat later - plus for any dietary issues. It's mostly just a communication thing.
When dd2 was that age, I usually fed everyone fairly early. She had a mate who frequently came round after school & was affectionately termed Dustbin by me & her own mum (a friend) - it was a standing joke that 'Dustbin' would eagerly hoover up whatever I cooked when my own fussy kids quite often picked at it.
Great from my POV - dd2 learned to be less fussy by copying her mate who was appreciatively scarfing down whatever I dished up.
Not always quite so great from Dustbin's mum's POV, as they ate later & her dd frequently went home stuffed (& loudly saying 'Corvus is a great cook, why can't you make chilli like Corvus?!').
So we'd text each other. If she was happy for me to feed her dd (& to eat later herself with her other, older dc) then all good. If she wanted Dustbin coming home hungry for dinner, I'd give snacks only & eat with my dc once she'd gone home.
If dd went round there, I knew she'd get snacks but not an evening meal unless it was a sleepover.
It all worked out fine. I think part of the parenting experience at this age is they start hanging out with different families with different routines. It's helpful if you know the expectations, but really what's the worst that can happen?
You collect a dc who a) is hungry & the rest of you have eaten = a quick cheese toastie & fruit or b) you collect a dc who doesn't want their dinner = unless you're routinely serving up fillet steak, a portion of spag bol or curry goes in the fridge/freezer/dog...