Forcing theme change

You can do it in the database: https://designgala.com/how-to-change-wordpress-theme-directly-from-database/

Basically go in via phpMyAdmin and edit wp_#_options (where # is your site number) instead of just wp_options.

OR.

Network Admin -> Sites -> Edit Site

Click on settings and look for Current Theme – I will note I THINK that you have to use the full name, caps and all, to make that work.

You may also need to edit Template and Stylesheet

Good luck!

There isn’t a plugin to help, no.