All my dozens of plumeria have to come inside to overwinter. Mid to late October is usually when that process begins. I have tried all kinds of ways to overwinter them, and have posted lots of times about what I do.
If you have to bring yours into the garage and the soil is still moist, I would sit a box fan several feet away and run it 24 hrs. a day so that the air movement will speed up those leaves' transpiration and thus draw moisture from the soil. If you have a way to keep the temperature at or above 60F, if these is adequate light, and if there is some air movement, you can continue to grow your plants, though they will go semi-dormant. You'll just keep the potting media slightly moist and occasionally mist the leaves. The alternative is to simply allow those plants to go dormant and keep the soil dry as a bone. All the leaves will be lost, other than the tiny, terminal ones. You may still get that one with an inflo to bloom. I have had my dormant plants bloom without water and without leaves. The blooms will be kind of puny though.
Other than for new seedlings, I have never really attempted to actively grow any of my plumeria over the fall/winter months. This year, with a new solarium available, I plan on doing this with a handful of my plants. I am picking the ones that are in bloom (I love the flowers and the frangrances). I will be able to post my results next spring.
This is the set-up I had last year in my garage, a 6x8' "temporary" greenhouse. It will be increased by 2' (at least) this year. The "greenhouse has a 2x4" base, 2x4" framing, and a solar blanket material covering. It has super-insulation value and required very little heat, even when the outside temperature dipping into the mid-teens.
The above is what I have experienced and is only based on my growing conditions and trial-and-error growing. Others will have different ideas, different experiences, and different results.