One of my outdoor plumerias has small trunks. Anyone have any thoughts on a way to fatten them up. The lower portion of the branches have smaller diameter so concerned it won't be strong enough to support later growth.
If I go the cutting route, can I expect new growth from the remaining main trunk?

It will fatten with maturity. I wouldn't be too worried about it if it is healthy.

@Kalamodo with Jason! Once the plumeria gets bigger you will not notice it that much.

Perfect. I didn't want start a new cutting so will leave it as is. Thank you.
Just curious. If the main trunk were to be cut or snapped below the branches (e.g., middle of trunk) do plumerias produce new growth? Or is it lost.

As long as it is an established plant with good roots, yes it will push new branches.
Example

You're welcome. Welcome to the forum!