If we agree to a property settlement and custody now, is it possible to modify that at a later date?

My thinking is the property settlement was the biggest hurdle and we've agreed to no child support or maintenance either way (large income disparity w/ me earning less).

Once I can establish a home in the children's school district, I'd like to modify the child custody agreement seeking a more even 50/50 arrangement and ask for cs and maintenance.

Didnt known if we finalize this now, if that would be off the table later when I seek to modify it.