Time Zone support on iPhone

I find it frustrating that Apple does not allow for the "floating" time zone on mobile IOS - as it does on MacBook. I travel constantly between time zones and have to use my laptop to update all appointments I add on my iPhone - as there is no option to choose a time that floats between timezones on mobile devices. I have mentioned it several times to Apple staff in the stores. No one knows why a fix has not been included for mobile devices.

Can someone sort this out please?

Thanks for your help!