Welcome Sunshineinphx,
Thank you for using Apple Support Communities. Based on your post, you'd like to know if your time stamps for previously sent or received messages will change if you change time zones. We'll do our best to assist with this.
From what we can remember while traveling between time zones, the iPhone will update the time as you travel. Which means, if you sent a message at 8 am EST, but then traveled to CST it would automatically update to the new time zone (CST) along with your messages. This only happens unless you've changed it from Automatic in Settings > General > Time & Date > Time Zone > Set Automatically: Set the date and time on iPhone
Basically, yes, the messages will update that time stamp, given your new time zone.
Hope that helps out, take care!