In the Style Tab (or somewhere else?) there should be a RTL (Right To Left) toggle, for Arabic and Hebrew.
There's also this question which can be used as reference: https://github.com/voidlabs/mosaico/issues/406
You probably can do that by altering the master template.
I close this and leave only #406 for the same feature request/question. Contributions are welcome.
In the Style Tab (or somewhere else?) there should be a RTL (Right To Left) toggle, for Arabic and Hebrew. There's also this question which can be used as reference: https://github.com/voidlabs/mosaico/issues/406