Now Google is in the process of rolling out the new look for Gmail.
The new look will appear to users gradually whether they like it or not, but there is still an option to go back to the previous version afterwards.
The idea is that the new look should make it easier for users to move between apps like Gmail, Gchat and Google Meet without having multiple tabs or windows open at the same time.
The layout of the appearance will largely be based on which edition of Google Workspace you have. If you only have Gmail, you will still only have the Gmail configuration in the future.
It may take over two weeks before the new look is available to all users.