A good doctor will ask you if you have any questions.
And a good doctor will listen - really listen - when you talk.
He/she won't rush you.

About 10 years ago my old doctor retired. At my first visit with his replacement, the usual examination things happened. He checked my blood pressure, listened to my breathing with a stethoscope, etc.

After the examination ended, he sat back in his chair and said, "Do you have any questions?" That was a good sign. And he turned out to be a good doctor.

You might want to do a Google search for "How to choose a doctor" for more ideas. Here are some good links:

https://www.webmd.com/health-insurance/how-to-choose-a-doctor#1
https://www.bcbs.com/five-tips-choosing-new-primary-care-physician

For something that is a "few years" away.

A lot can happen in a few years. Your doc decides to work longer, the new doc leaves medicine, or moves to a location you can't reach, or your insurance changeys and the new doc is no longer in network (or the insurance stays the same, but your doc terminates his contract with them), or the new doc stops accepting new patients.

If you're ready to change now, even if your doc keeps working for a while, or if your doc is ready to retire within a year, or you need a second opinion about something, it makes sense to scope out other doctors - but not for a potential new doc a few years out. That's a waste of their time and yours.