Which company can I purchase "front of the line" museum passes from while in Rome?

Which museum(s) is/are you interested in?

Yes...we want to see multiple museums/attractions. We will be in Rome for 5 days. Colosseum, St. Peter's Basilica, Vatican City/Museums, Sistine Chapel....all the really historic beautiful buildings that one pays to see. Thank you.

Check Walks of Italy. The tours are great and you get skip the line tickets.

You can buy reserved tickets ahead of time directly from the Vatican Museum, Borghese Gallery, and the Colosseum/Forum. See also https://www.ricksteves.com/europe/italy/guidebook-updates. The Roma Pass has a lot of restrictions, making it not really a skip-the-line pass, and it never covered the Vatican Museum, anyway.

The Roma Pass has a lot of restrictions, making it not really a
skip-the-line pass, and it never covered the Vatican Museum, anyway.

Ditto what Laura has advised. For pre-purchased tickets to the attractions which either require or highly suggest them for avoiding long ticket lines, you should go to the OFFICIAL ticket sites for each:

Vatican Museums:
http://www.museivaticani.va/content/museivaticani/en.html

Colosseum/Forum/Palatine:
https://www.coopculture.it/en/

Galleria Borghese:
https://www.tosc.it/tickets.html
Advance reservations are mandatory for this museum.

The websites above offer both organized tours and general-entry tickets. Other attractions in Rome are unlikely to have long ticket lines.

Thank you all....your suggestions are what I will do...
Can't wait to get there. Travel on everyone...
Thanks so much.

Definitely purchase ahead of time for the Vatican Museum, Borghese Gallery and Colosseum