Good morning,
I noticed my plumeria has soft sections on the branches. My other tree, about same size is firm too to bottom. The he plumeria in question looks wrinkled in the areas of soft and squishy areas. Should I water less and possibly dry out, or is this a problem that I may lose my tree?

Hard to say if it is rotting, or just dehydrated. Maybe try a pin prick on the wrinkly area. See if it bleeds white sap or not. It's possible that it is underwatered. Wrinkles on the stem aren't a serious problem unless it's actually rotting. If it is, then you will want to cut off the branch above the rotting section and reroot it. Also, cut below the rotting section to ensure it doesn't spread down the branch to the trunk. It will grow new branches from the cutoff.