Set all files in Sharepoint to a specific Sensitivity Label

I have just started with MIP for a site and the customer wants all the labels set in Sharepoint Online to one default Sensitivity label. A few labels are already set, so ultimately all but these ones should be set, but as said few, so I can set them again. How do I do this?

The background why I ask is because I have read in this Microsoft document “Use sensitivity labels to protect content in Microsoft Teams, Microsoft 365 groups, and SharePoint sites”, that the files do not inherit the labels if I use them on a container: “Content in these containers however, do not inherit the labels for the classification or settings for files and emails, such as visual markings and encryption.” So I guess that means they only apply to the folder, and if the files are moved they do not keep the label?

The other way that I have found that could maybe do what I want is auto-labeling policy. But for starters when I go to Compliance center/Solutions/Information protection, there is no Auto-labeling tab.

So, is there any way that I can do what I want?