When the new Media Gallery is enabled, the Media section appears with a single option to access the Media Gallery. You can set the Enable Old Media Gallery option to No
by going to Stores > Settings > Configuration and choosing Advanced > System in the left panel.
On the Admin sidebar, choose Content.
The Banners option in this menu was deprecated in 2.3.1 and is now removed. Its functionality is replaced by Dynamic Blocks.
Manage the visual presentation of your store:
Set the Design configuration to maintain different settings for each website, store, and view in your Commerce installation.
Use themes, which are collections of layout files, template files, translation files, and skins, to determine the visual presentation of your store.
Use the schedule to plan theme changes in advance for a season or promotion.
Content staging gives your business team the ability to easily create, preview, and schedule a wide range of content updates directly from the Admin of your store.