Your sentence is almost perfect. Did you know that The Princess Diaries 3 is coming out soon? I'm looking forward to seeing it. We'd add 'The' in front of the movie name because that's part of the official name. We usually say a movie is 'coming out soon' or 'being released soon' although the first is more common. Because this sentence is more likely being said in a casual context, maybe speaking with friends, we'd likely say 'I'm' instead of 'I am' which is slightly more formal and longer.

Did you hear that The Princess Diaries 3 is being released soon?

Georgia’s answer is perfect. In addition, movie titles should be in italic font.