Follow the steps bellow to turn your WordPress Website into an RTL compatible website.
Go to to Settings > General.
For the Site Language choose any RTL language like for example Arabic.
At this point both the backend and the Frontend will have RTL layout.
In addition to this, if you want to have your Backend in standard layout, but in the same time to keep the Frontend in RTL format, follow these steps:
Go to Dashboard > Users
Edit your current username
Set English as the Language option
Note: if some of the modules still have the LTR format, please check Design Tab of each of those modules and make sure the Text Alignment is either set to Default or Right Alignment.