At 5 my oldest son is doing a lot of small chores around the house. He just passed the tipping point of where I can spend less time giving him directions than it would have taken for me to just do the job myself. I see this scaling over time.
A part of the "playing" that I do with him is building and repairing stuff around the home. He loves it. It takes much longer to complete anything that if I was just doing it myself, but I'm doubling up "play" and "chores" so it works out. For things that he can't help with I try to outsource.
I like some of the ideas of past generations who often viewed kids as resources.
There should be a way to borrow someone else's kids for 6 months or so, force yourself to carve the waste out of your life... and then wait another decade before having your own kids.
You'll learn tricks to improve your performance and squeeze more time into the day. But the biggest thing that's worked most for me is staying up later than I normally would prefer. I get a few extra hours for passion projects and still get everything in the day accomplished that I'm required to accomplish.
It's a tough slog. Immensely rewarding, but tough. Prepare yourself for the change in advance so that you don't go through the massive shock I experienced.