What are the companies that offer 4-day work week

Maybe look for the more general case: companies that focus on people finishing their tasks on time and adding value, rather than when or where they work.

In my experience in the biz (four decades) I’ve found almost every employer amenable to flexible hours and working from home for people who can get their work done without constant supervision.

I can’t tell if you’re asking about 4 8-hours days a week, which is less than full-time, or 4 10-hour days. Probably few companies offer this in their job postings, it’s the kind of thing you negotiate during the hiring process.