My husband grew up in Philly – in a 1300 sf 3br row house… one of 6 kids… And that was typical for their Italian neighborhood.
We bought the house I grew up in from my dad. It’s just over 2000 sf, 4br. We have 2 kids and still have a spare room to use for guests. (Which gets used a lot!) We’re a family of 4. But growing up I was in a family of 5. It never felt cramped… I had friends with bigger families in smaller houses.
Prior to buying this house, we rented a 1500 sf 4 br house AND had my inlaws living with us… but only had 1 kid at the time… I will admit that it was more cramped – but that has more to do with 4 adults, one in a wheelchair needing care, puts stress in a situation. It had less to do with space.