Yes! You can make this change within your Slack Preferences by clicking your profile picture -> preferences -> Language & Region -> change the Language to your desired choice.
We derive your locale from your Slack settings. For example:
If you have it configured to the English (UK)
You would get a date format of DD/MM/YYYY and a 24 hour time format
If you have it configured to English (US)
You would get an MM/DD/YY format and a 12-hour time format
