A VW Golf from the 2020s could not cover that use case legally or practically.
First of all, kids need safety seats nowadays and these seats are to be mounted via ISOFIX. And guess how many such seats you can mount in a Golf? Right. Two. When the kids grow older, they don't need such seats but need to be belted properly, potentially including another form of a cheaper safety seat or a particular kind of belt, depending on the jurisdiction. You might consider this some kind of circus or greed, but when it's about safety of my children, I don't go back 50 years just because we all need to be more sustainable while some people (cough, US, cough) seem to think it's a great idea to live in uninsulated homes running their AC on fossile fuel.
Besides that, small children need strollers and more children generally means more luggage. You could get away with a Passat or a Golf Variant, but you'd face a challenge for longer trips. A family car exists to solve a problem and not to cause trouble.
And regarding renting a van: This would easily cost more than ownership (weekend trips are horribly expensive) and be less comfortable (fetching and returning the car).