Tor: Does Tor Browser protect other apps on my computer?

Short answer

No. Tor Browser routes its own traffic through Tor; other browsers, messaging apps, updaters, and document viewers use their own connections unless configured separately. This matters when a downloaded file opens outside the browser. If you need system-wide routing, research an operating system designed for that purpose rather than assuming Tor Browser changes the whole device.

Sources

Tor Project: Managing identities, Tor Project: Tor Browser best practices.