I worked at 2 companies with unlimited PTO and didn't like the experiences at either company. In reality, there would be a real number management expected you not to go over.

I would take more PTO than expected and then get verbally told, "for your position, you are taking more than your peer group."

What I would do is have an upfront discussion with your manager to clear out what is within expectation. Is it 3 weeks, 4 weeks, 5 weeks?

The problem with unlimited PTO is that sometimes you can feel guilty taking more, because you aren't entitled to it unlike a set of PTO you would get at any other company.