Tim Ferris got famous (arguably) writing a book about this. It's a bit winding and some of the content is out of date, but the general concepts are good - Four Hour Workweek, probably most here have already heard of it / read it though.
I'm mildly surprised at people's skepticism though, this has been a thing for a while.
His main point is to have people start their own businesses. Whereas what I'm talking about (and in fact also wrote a book about: https://codewithoutrules.com/3dayweekend/) is working shorter hours while still being an employee.
Well, I won't argue what the main point is, I have no idea (I remember the book as being very meandering). But he definitely addressed how someone should get less hours at their job. As I recall:
1. Find an excuse to work from home. Sick, doctor's appointment, just say you wanna work from home, whatever.
2. On that day, get more work done than you've ever done before.
3. Do this consistently.
4. Request regular fridays off, point to your increased productivity.
5. Rinse and repeat until you're totally remote.
6. Reduce actual working hours, taking advantage of less distracting environment and more flexible hours to maintain productivity.
The problem with this is that his book is at this point well known, but at the same time his book made less (but still productive) work more socially accepted, so it's better to just go the honest way.
To take a sick day off? I don't really remember, don't let me put words in his mouth. As I recall it was framed like "find a way to get a day off. Wait until you need to take a sick day if need be."
I really wouldn't read too much into my decade-old-take. I read the book last in 2014.
This was from memory, and my recollection is he then segues into "and now use this free time to start your dropshipping business or whatever". Perhaps I'm misremembering, though.
I think you're right - it was something like "now you have all this free time, you can do this drop shipping thing to make yourself totally independent of work. Maybe you quit one day!"
I'm mildly surprised at people's skepticism though, this has been a thing for a while.