Setting up membership levels at sign-in

Im using Wix studio and want to set up my member login with a dropdown that allows the user to determine which membership level they receive.

For example,
I want the member sign-up form to contain a dropdown to give three different options(individual use, leading a group, or leading a campus). If someone chooses “leading a group” I want their member role to automatically be set at a specific corresponding level. Ideally I would be able to have 3 different member roles and based on what a new member selects on their sign-up form, they would automatically be given a specific role.

I don’t want to have to manually set everyones role when they sign up.

Would need to code I believe.
You could create a custom sign up page and then save the level as a custom field or use the badges API