Datetimeoffset defines a date that is combined with a time of a day that has time zone awareness and is based on a 24-hour clock.
If you would like to represent the same time 5:00 in the afternoon in Colorado in May, in a datetimeoffset variable, you can do it this way:
DECLARE @t DATETIME = '2019-05-21 17:00:00';
DECLARE @London DATETIMEOFFSET;
DECLARE @Colorado DATETIMEOFFSET;
SELECT @t AS InputDate_5pm_24h_clock;
SELECT @London = @t AT TIME ZONE 'GMT Standard Time';
SELECT @Colorado = @t AT TIME ZONE 'Mountain Standard Time';
SELECT @London AS London_5pm, @Colorado AS Denver_5pm;
-- Results --
21/05/2019 17:00:00 +01:0021/05/2019 17:00:00 -06:00
Thanks, for this interesting question.