Can a 16“ MacBook Pro be reverted to an OS before Catalina?
The 16&quot; MacBook Pro cannot run anything earlier than Catalina.

Sometimes you can “downgrade” the operating system on a new Mac to an earlier version of macOS, but you should never count on it.

If that Mac is completely new hardware (like the new 16&quot; MacBook Pro) then Apple never adds driver support for older versions of macOS.

If you order a Mac which could run an older version of macOS, even though it comes installed with a newer version of macOS, it might be able to downgrade.

For example, if Apple released a minor update to the 2019 MacBook Air line, and you ordered a new MacBook Air and it arrived with Catalina on it, you might be able to install Mojave on it. But you would never be able to install High Sierra on it (in fact the 2019 MacBook Air cannot run anything older than 10.14.5).