Microsoft has just released in modern SharePoint Online (SPO) document libraries the new Filters Pane that allows to apply smart filters in a very productive and intuitive way to any content stored in a modern document library:
In order to start using this new Filters Pane, just click on the Filter icon avilable at the document library actions bar:
This Filters Pane allows to apply filters based on default columns available in the document library. Each filter is represented using a visual control that is related to its data type. For instance, a date column is represented with a slider control:
And of course, we can add additional filters columns in the Filters Pane. To add a new filter column in the Pane, we only need to select this column in the document library view and then click on: Column settings –> Pin to filters pane.