Use filters to change your view of files or list items

As we continue to update user experiences and customizability in SharePoint document libraries, we are pleased to announce the inclusion of metadata-driven filtering to the filters pane, originally introduced in late 2016.

https://techcommunity.microsoft.com/t5/SharePoint-Blog/SharePoint-filters-pane-updates-filtering-and-metadata/ba-p/74162

https://support.office.com/en-us/article/Use-filters-to-change-your-view-of-files-or-list-items-293561ed-fb2e-4fb2-9a9f-8a21e299e323