Whenever we want to convert opportunity into rental, generally we do it by going into the Rental module. But now this can be done directly in the CRM module itself.
If you want to convert opportunity into rental, then you can directly create it from the CRM, without going to the Rental module.
Let's see how this can be done.
Flow: Open the CRM module, then click on the opportunity. Along with other buttons (i.e won, lost) Odoo has added a new button called New Rental.
This is integration with the Rental module.
Once you click on New Rental Odoo will allow you to create a New Rental.
Now you can see the “New Rental” tab besides New Quotation. Click on it, then save the Rental which is created.
Odoo14 - New Features