I’m playing with modern experience and inside the document library. I found this option format view .
What can you do with this ? what are the possibilities ?
Improve the display of views in SharePoint lists with formatting. The view-formatting text describes the elements that are displayed and their display style. The data in the list doesn't change.
In other words you can create new formatted view, that can look completely different then the out-of-the-box one.
Using format view, you can format rendering of your library view. As in Previous version of SharePoint/Classic experience SharePoint developers are using Client side rendering(CSR) option to customize the List/Library view, you can achieve something similar to that using View Formatting(Format View) option.
You can use view formatting to customize how views in SharePoint lists and libraries are displayed. To do this, you construct a JSON object that describes the elements that are displayed when a row is loaded in a list view and any styles to be applied to those elements. View formatting does not change the data in list items; it only changes how they're displayed to users who browse the list. Anyone who can create and manage views in a list can use view formatting to configure how views are displayed.
You can get the samples for view formatting from below URL: