Virus Scanning Best Practices: Connecting an old Dropbox account to a new MacBook Pro

Be sure to read John Galt's reference in its entirety.

MacOS shares a lot of the lock-down mechanisms developed for the iPhone. Applications are all sand-boxed with a list of the resources they require, and they cannot ask for anything outside their sandbox without crashing. Signed Applications are checked that they are from legitimate Developers, and Notarized Applications are delivered with the assurance that they have NOT been modified since their release by the Developer.

From MacOS 11 Big Sur onward, the system is on a Separate, crypto-locked System Volume, which is not writeable using ordinary means. Any unauthorized changes (how ever they occurred) to the crypto-locked volume are quickly detected and you are alerted.

So you could store just about every malware known to mankind on your Mac, and your Mac would not get infected spontaneously. Scanning for virus-like patterns might make you feel a little better now, but non-stop scanning is outdated nonsense, and a tremendous waste of resources.

Nothing can become Executable Unless/Until you supply your Admin password to "make it so".

The macOS operating system has built-in virus protection. You don't need anything else.

There are no viruses that affect macOS.

Effective defenses against malware and other threats - Apple Community describes the best practices you seek.

And if you want to take a "belt and suspenders" approach, the free version of Malwarebytes, run from time to time, should, along with the protection built into macOS, be more than sufficient.

Regards.