Time and Date Stamp on Note9

Not on the stock camera (there is a Date stamp in the AR Emoji section, but no time). All pictures, however, ARE saved with timestamp information in them. You might use a 3rd party editing app to apply that timestamp based off of that.
 
Yeah, not a popular feature anymore... only apps that add a filter overlay (stamps) have something similar, but seldom time stamp (usually date or location are the popular option).
 
I use a program called Timestamp photo and video. It doesn't save the timestamp as you take the photo, but you can open up the app and easily add it. You can change font, font color, and font size. It has multiple timestamp formats and can place the timestamp in 6 different positions on the photo.
 
if you open the picture and then click the 3 dots up in the right hand corner and select details it will show you