Pipeline in GitLab

Hi Team,

I have created a pipeline that perform SAST scanning on the code whenever user creates a merge request to master. This pipeline present in the application repo and perform scan whenever merge request opened for that repository. However we want to globalize this pipeline and whenever merge request opened for any of the repository the pipeline should
be executed and should allow the merge to master only when pipeline succeeds.

How to create a pipeline that is applicable to all or subset of repositories or specific to particular project folder/subprojects/groups?