Speaking as someone in a similar position, it’s not possible. You can have young kids or have time. Not both. Which, sucks, given that what it sounds like you

Speaking as someone in a similar position, it’s not possible. You can have young kids or have time. Not both. Which, sucks, given that what it sounds like you actually want rather than time to grind leetcode and do side projects is to find a different job. But the way the industry is set up effectively precludes you from doing that, because as you’re aware, you need to have time to do stuff outside of work to get and prepare for interviews.