As other people have said, you can negotiate for this. I've done it at multiple jobs. Here's an interview with someone who has been doing it for 15 years: https://codewithoutrules.com/2018/01/08/part-time-programmer...

1. It's easier at existing job; you have all this knowledge that's hard to replace (https://codewithoutrules.com/2019/01/25/4-day-workweek-easy-...).

2. At new jobs, apply normally. Then _after_ you get an offer, ask for shorter hours.

3. I wrote a book about the process; it's no longer public linked on my site because pandemic has lowered negotiation leverage a lot and I'm not sure how to address that, but if you're interested: https://codewithoutrules.com/3dayweekend/