How do Virtual Reality headsets work if you wear glasses?

They have a frame that fits over glasses

You can adjust the focus.

It depends upon the set.
Some have diopter adjustments that range from -3 to +3 diopters. (My drone headset has that.) If not, they leave room for glasses.

You usually don’t need glasses when using a Virtual Reality headset.

@KRD how does that work? I need glasses to read, and glasses to drive. How does the VR work in terms of correcting my vision?

It has a roller you roll to correct the focus, until you can see clearly.