Sorry for the clickbait title.
On the top right corner of each message inside chat, is the time and date of when that message was sent. It should be your local time zone.
However, I have sometimes seen a player on a server that has a different time then others, as if it has different time zones/clocks. Like this player who is in the year 2069/1069/5069/etc. Specifically the green player. (Each color represents a different player.)
You might have to click the photo to see it fully. Other players on the server also experienced that green player to have the date 2069/1069/3069/idk. I want to say ALL, but I haven’t confirmed it.