You can significantly decrease the size of the log by disabling logging executed steps.
https://docs.katalon.com/katalon-studio/docs/working-with-execution-log.html
Log executed test steps
Starting from Katalon Studio version 7.0 , an option to disable Log executed test steps is available in Project Settings > Executions . By enabling or disabling this option, you can decide whether the logs include executed test steps or not.
By disabling logging executed step, you should be able to decrease the size of the log overall.
However, … see Project Settings > Executions > Enable/Disable logging executed steps; is it deprecated?