Is there an easy way to combine/merge two roles into one?

Fire one member of a two-person team? 😂 All kidding aside, Setup > Users/Roles > Show Role Differences is really helpful in finding what's different. You can export this list too and then use that to update the role you want appropriately. As far as entering/changing the role, not really. I think they figure you're not going to be updating roles that often.

if you've got a dev or technical admin on hand, they could do this via SDF. Although if you're not doing this in bulk (and why would you be 🤷), you're best off doing the 'show role diff' that James mentions and then creating a new role/updating the existing by hand