How to specify time zone for scheduled realm trigger using CRON?

I checked the documentation and it says that scheduled trigger uses standard cron job syntax. However, when I tried to specify the time zone using CRON_TZ=ET or TZ=ET it didn’t work. I can’t use UTC since my trigger depends on the concrete time in the time zone which has daylight shifts. For now, it’s ok to change all my trigger times twice a year but I prefer to automate this.