Not his properties presently, but I doubt the GE pension trust scouts out the project and procures it and starts the development of it.
I know several people who do what Trump does, on a much smaller scale. They are the feet on the ground who find a development site and design it and get it started and completed. If at any point along the way, they syndicate it or find investors to join them then that's what they do.
Some projects are completed and kept in the developer's portfolio. Some are sold off. Sometimes the developer likes the finished product and keeps a stake. And, yes, I know someone who puts his brand name on every project. He's built a track record and the name attracts new investors so he can keep the ball rolling.