Since GitLab for Kubernetes is configured by Helm charts, you need to configure all settings through that.
The options can be found here: https://gitlab.com/charts/gitlab/blob/master/doc/installation/command-line-options.md.
For each set of options, some are required, and those that are not required have a default value.
In the next section, we will pick some of the options to change in a Kubernetes environment.