Q.I Live In Whittier, CA (zone 10a Or B) And Want To Move My Plumeria From Pot To Ground.
It would get plenty of sun, middle of the lawn. i wonder about winter, which doesn’t go below 35, is still too cold for it. It is doing well in a pot. We get temps of over 100 degrees in summer sometimes. I think last year I put it in the garage when it was going to be cold and frost.

Certified GKH Gardening Expert
It's best not to expose it to less than 40 degrees F. One hour at 32 degrees F can kill it. You can always plant it in the ground in spring, either in or out of the pot, then dig it up in the fall and bring it in. Some people leave it in the ground then cover it when temps plunge, but you sure wouldn't want a freeze to sneak up on you and lose your plant. You can leave it in the garage all winter and let it go dormant. Or leave it in the house and let it go dormant.
https://www.gardeningknowhow.com/ornamental/flowers/plumeria/growing-plumeria.htm