I recently acquired a Mini 2 and I have a question about the geo zone alerts.

I’m in a class B zone and the App shows a max of 60m flight altitude. The question is, do I need to request permission if I want to flight under the 60m? let’s say at 30m?

No, you are good to go up to 60M in that zone.  

Happy flying.  

In that scenario, 60m is the Maximum height you can ascend to. So anything less is also OK.