Our roof has these wooden support beams which are a pretty rough cut wood, I was wondering which electrical sanding tool would be the best for something like this, an orbital sander, belt sander...? Thanks!
I would use a seven inch disc on a large angle grinder. It's super aggressive, def will be the fastest. A bit hard to control, and easy to have it dig in, so practice where you can't see it. Your arms will feel the burn after.
Unless they are going for a distressed finished look, this is a horrible idea. Even with experience there is no way you'll get a flat finish; without experience you'll have deep pockets and very uneven, rounded corners. Maybe slightly faster than a belt sander, but it'd be negligible and definitely not after all the finish sanding that will be required after.
I've done several timber frames and refinished a dovetail log home with an angle grinder. You can achieve a flat finish with care, and the time difference over a belt sander is far from negligible. But it is perhaps a bit tricky for a beginner.