Instinct collects body (wrist skin) temperature and displays a 4 hour trend but Connect doesn't.

Can you display a long term body temperature trend with Connect?

Only during an activity. If you need it for longer periods during the day, create a custom activity, preferably without GPS (not to drain the battery too fast), and let the activity run as long as you want to record the temperature. However, it is not really the body temperature, rather the temperature of the watch sensor - it is influenced not only by the body, but also by the ambient temperature, by the air circulation, and also by the inner heat of the watch electronics.