Hello!
Is there a way to choose a Role first before the Registration Form for the specific roles comes out?
Sorry this is not available as of now.
By default only students are registered on the site.
If you want to register instructors on your website you can use the ninja forms and can refer this video tutorial:
https://www.youtube.com/watch?v=fEdUsMg4A5g
Thank you! Can I also add another role aside from student and instructor using this form?
You register different users using ninja forms plugin.
You can refer to ninja forms documentation and ninja forms support forum for this.