Can we maintain CI/CD script and source conde separate repository

Hi Team ,

My self Jayaram. 

Can we maintain src code and CI/CD code in separate branches.

While triggering pipeline manually  it should show all branches listed in to the dropdown and we should be able to select which branch I want to trigger.

is this possible in Bitbcuket. 

If i am mentioning like below :
branches:

      develop;

If am mentioning like this , I can see in dropdown only develop. If i mentioned all names. all branches will trigger. 

How can i achieve this in bitbucket. 

Thanks & Regards,

Jaya Ramarao S.