That depends on how you are comparing the data. If you are comparing them as strings (ie you want to use the raw data as it comes from the API), then yes you would need to convert your comparison data to the ISO 8601 format which would present it as a date and time string in UTC. If, however, you compare the data as actual time values (ie milliseconds since epoch) then no you wouldn’t need to convert the comparison data to UTC. The actual time value doesn’t change, just the display value.
For example if the change was logged at 8am Central time in the US then it will be presented as having been made at 2pm UTC, as those two values represent the same time instance.
In this latter comparison scenario you would need to first parse the API delivered ISO 8601 datetime string to an actual datetime type, but most languages have built in support for parsing ISO 8601 strings to dates. For example in JS it would literally just look like this.
var dateString = "2016-02-22T14:00:53Z";
var jsDate = new Date(dateString);
I hope that makes sense.