I'd budget 3-4% of a homes non-land cost for maintenance. You can find the value of land and the improvements (i.e., the home) online. It should be public record.

If the home has lots of land or expensive trees/plants/flowers you can add more to maintain them.

Best thing I ever did was buy a small house I liked and dump money into it to make it the way I wanted. I recently sold it but, man, did I love that house. The size and low price meant I could keep putting money into it to make it just the way I wanted. Didn't quite get there as the fence still needed repairing and wood prices soared so much during COVID I skipped that part.

But I loved everything else I did. And there's no way an apartment would ever look like what I did with the house.