My MacBook Pro is backed up to the Cloud. Is this sufficient before I bring my computer in for service?

MacBooks cannot be backed up to iCloud. You may have synced some files but you do not have a backup.

backup your Mac using Time Machine and an external drive How to back up your Mac - Official Apple Support

Apple offers iCloud Backup for iPhones and iPads but not for Mac computers.

It is possible to sync data from a Mac to iCloud if you turn on those options (e.g., iCloud Photos, iCloud Drive including the Desktop & Documents option). Syncing has some of the benefits of a backup (and the benefit of being offsite) but is not the same as a backup. Major differences include the fact that not everything on your Mac can be synced and the fact that if you delete something, accidentally or otherwise, there is only a limited time period (30 days in most cases) during which it can be recovered.

Regarding taking a computer into service (or even risking loss of data at any time due to any issue), only you can determine if you have something on your Mac that you wouldn't want to lose and that isn't synced with iCloud.

But if you have any question about that, I will be glad to try to help.

Also see: How to back up your Mac - Official Apple Support

And more information on syncing in:

Set up and use iCloud Photos - Apple Support

and

Access and manage your files in iCloud Drive - Apple Support

and

Add your Desktop and Documents files to iCloud Drive - Apple Support