Chinese Elm Trunk, #2341

Chinese Elm trunk from SBBK Green Elephant for $10.

Need a plan to develop this. Is there nebari below—inspect during repot. Keep upright or with some angle.

Taper: will take time, select a new lead and pump with fertilizer. May angle trunk chop and leave the leader(s) in the direction desired for the trunk—ensuring the current branches are hardened off. Do this in late winter before bud swelling.

Fast growth you will get if you do this before bud swelling. To get tapering and to get the trunk to heal after the trunk chop, you need A LOT OF growth.
Chopping prior to bud swell because the tree uses its sugar storage to push the buds - if you do later, the tree would have spent the energy pushing those buds, which you will then cutoff before it gets its investments back, and the tree will be in energy negative for the rest of the year.
Bonsai Empire comments

Let whips grow long and see if thread grafting a lower branch would help—primary. Focus on new leader and primary branch(es).

If cuttings can be grown, can approach graft as new roots to create nebari. Added a ring of sphagnum moss below the soil line to encourage root nebaru, if possible. Could not hurt.