Making a drop down of membership levels

You’d need a custom checkout template and to write the custom form with Javascript to ‘change’ the level being checked out for.

Jason and Jess in our members only support forum can provide direction as part of PMPro Membership via our members only forum here: https://www.paidmembershipspro.com/forums/forum/members-forum/

Alternately, we offer a Little Help package that would include this customization for your unique setup. See: https://www.paidmembershipspro.com/little-help/