Yes you can. If you click on your profile, and then Settings->Applications->Configure you can see the permissions If you have it installed for an organization

Yes you can. If you click on your profile, and then Settings->Applications->Configure you can see the permissions If you have it installed for an organization its slightly different. Go to the organization, then Settings->Github Apps->Configure. For me at least, it lists the permissions the app has. Additionally, if we ever want to request new permissions in the future, you will have to grant them.