Gitlab's git merge algorithm config


We have an issue with git merge requests. We are using Gitlab on kubernetes (gitlab as a docker image). Is there a way to change the git’s merge algorithm which Gitlab uses?

We tried to change the merger - git-json-merge which we are successful in doing on the container / pod where gitlab is installed. But, upon performing merge we noticed that gitlab is not using the git installed on the container?

Is there a way to change the merge algorithm?