Hi there,
Can you advice how to do this in CLI
Please note that using CLI to run the database update would depend on if your host allows using commands to perform tasks in your server. It also requires technical knowledge to run CLI to make the update. Be sure to make a full site backup before proceeding.
I found an external document that shares steps to update your Database via CLI. You can read more on the steps here.
Is there another way than turning off my entire site, seriously…
I understand your concern about disabling plugins for a conflict test on your live site. While this is the most common method, you may also perform a conflict test by creating a staging site – a complete copy of your existing website. This allows you to test the changes without affecting your live site.
However, please note that creating a staging site might require some technical knowledge as well. You may find the details to creating a staging site here.
Let us know if you need further assistance.