Q.What Flowers Do Well With Plumeria?
Have 2 plumeria plants would like to plant them next to my garage. Should this be a problem for the structure?

Certified GKH Gardening Expert
They don't normally cause any structural issues. That will be fine to plant near structures. Many plants pair well with Plumeria, as long as they have similar requirements.
Here are some articles that will give you information on some of the most common companions:
https://www.gardeningknowhow.com/ornamental/cacti-succulents/epiphyllum/epiphyllum-plant-care.htm
https://www.gardeningknowhow.com/ornamental/trees/brugmansia/growing-brugmansias-in-containers.htm
https://www.gardeningknowhow.com/ornamental/bulbs/elephant-ear/growing-elephant-ear-plants.htm
https://www.gardeningknowhow.com/ornamental/foliage/cycads/growing-cycad-plants.htm
https://www.gardeningknowhow.com/houseplants/crown-of-thorns/growing-crown-of-thorns-outdoors.htm
This article will help you care for Plumeria:
https://www.gardeningknowhow.com/ornamental/flowers/plumeria/growing-plumeria.htm