I once made an interesting little thing out of another Dracaena (the common D. marginata) by rooting it in water, then draping those over a buried rock, planting the lower parts in soil mix. When it was well rooted into the soil, I started raising the rock (actually just removing soil mix a little at a time over a few months), and trimming off the higher roots until just a few of the lowest ones were left where I wanted them. The trunk was bent a couple times back and forth by using a nut/bolt and wire (with padding).

Maybe not a "true" bonsai, but it looked very Chinese style somehow, especially after moss started growing on the rock, when it was in a greenhouse for a while. The newer leaves and upper trunk stayed smaller than the lower part, because of lower feeding and watering. It looked pretty nice after the old larger leaves were removed. Eventually I killed it by forgetting to water, without getting a picture.

I have no idea how long it would take to get a tree-looking trunk on a potted Dracaena, but I bet it would take a lot of patience.

I don't think a D. draco would ever bloom while being kept small in a pot. Dracaena can usually be forced to branch by cutting the tops off, or a with more natural look by nicking the stem above a dormant bud. Maybe faster by putting 'Keiki-Grow' or a similar hormone on where you want a branch, but I haven't tried that.