Accidentally pressed close all tabs rather than new private tab on mobile browser

[Mattches]

Unfortunately no, there’s no wya to do this. Note that you definitely should have seen a prompt to undo closing those tabs, as shown here:

No way to undo tab close on Android

This feature is already present. In the recording below, I’ve opened a new tab, closed it, then tapped the Undo option that appears at the bottom afterwards: