booking a room TimeZone

I am trying to modify Book A Room template. But I have a problem with Timezone, as the offices are in different countries, the app should work with local time. Would you advise me on how to fix it?

If(IsBooking,
UpdateContext({ShowLoading: true});
If(!BookForMeeting,
Office365.V2CalendarPostItem(MyCalendar, Subject, //User().FullName & "'s Booking",
//StartDateTimeUTC, EndDateTimeUTC,
DateAdd(StartDateTime, -TimeZoneOffset(StartDateTime), Minutes),
DateAdd(EndDateTime, -TimeZoneOffset(EndDateTime), Minutes),

// {//TimeZone:"Central Europe Standard Time",
{TimeZone:"Coordinated Universal Time" ,
RequiredAttendees:SelectedRequiedAttendees & RoomsGallery.Selected.Email,OptionalAttendees: SelectedOptionalAttendees, Location: RoomsGallery.Selected.Name, Importance: "Normal", ShowAs: "Busy", Body:Message, IsHtml:true});

Office365.SendEmailV2(User().Email, User().FullName & "'s Booking "&
//StartDateTimeUTC & " " & EndDateTimeUTC,
DateAdd(StartDateTime, TimeZoneOffset(), Minutes)& " " & DateAdd(EndDateTime, TimeZoneOffset(), Minutes),
"Location: " & RoomsGallery.Selected.Name & " " & "Orders: " & Text(Concat(SelectedOrder,Orders,";"& " ")) &" "& "Order Number: " & OrderNo & " " & "Automatic email from SharePoint" ,{IsHtml:true } );

Thanks in advance