If you read the Wix pages about Job Scheduler then you will see that Sam is correct.
https://support.wix.com/en/article/corvid-scheduling-recurring-jobs
Time (String)
The time of day the job runs. The time is specified as UTC time in HH:MM format.
Therefore any time that you set in the Cron will be in that UTC time format.
executionConfig (Object)
An object containing information about when the job should run. You can define when the job runs using a cron expression or by specifying a time of day and optionally a day of the week or date in the month.
Important:
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Jobs occuring more than once a day must be defined using a cron expression.
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If both specifications exist for a single job, only the cron expression will be used.
Cron Expression
When using a cron expression to specify when a job runs, the “executionConfig” object contains a single property, named “cronExpression”, whose value is a valid cron expression.
cronExpression (String)
A valid cron expression . For example, to run a job every day at 8:00 in the morning, use:
"cronExpression": "0 8 * * *"
Important:
When using a cron expression, you can schedule your job to run at intervals as short as one hour apart, but not shorter. If you define your job to run more frequently, the job will be ignored.