Gitlab-runner specify file when using log output of json

Hi there, been using Gitlab for a few months and am building a new AWS-based Gitlab environment including autoscaling runners etc.

Part of my remit is to get log files for GitLab and the runner managers into Splunk.
Currently I am simply sending the runner instance syslogs into Splunk but there’s a lot of rubbish along with the specific gitlab-runner entries that I want.
I eventually stumbled across the information that you can set log_format to use json, which is great, but it still puts the entry into syslog, resulting in a mixmatch of the 2 different formats (syslog and json).

Is there an option to output gitlab-runner logs to an alternative location when specifying a different log level or format that I just haven’t come across?