Calendar Issues while traveling
Most third party calendar tools on iOS offer this. I can really recommend fantastical, which offers the option you're looking for. See this site.


  Time Zone Override: When enabled, Fantastical will always show dates and times in the selected time zone. When disabled, Fantastical 2 will use the time zone configured in iOS's Settings app. This option is useful if you are traveling but still want to see your schedule in your home time zone.