Yes, it is a perennial and will die back to the ground every year.
It need substantial cooling period (from the memory, about 120 days of below 40F) in order to prosper and they are not well suited for z8 and higher, though some people in GA manage to grow it.
Ben Franklin will be about 30" tall and as wide in 3-5 years if you could meet cooling requirements, so plan accordinghly.

Hi, if it dies back to the ground every year, then how can it get bigger in later years?

Thanks

They have underground 'tubers' that will increase in size and produce more and more flowering stems every year.
In proper conditions and if left undisturbed it may last for 100+ years and be as big as 7-8' in diameter.

I have mine (was originally a 1-gallon plant) in a somewhat shallow 14" pot. It bloomed last year - a year after planting and has buds on it now. Finally got a peony hoop for it and am training the stems through the grid.

If you use a 20 inch pot it should be OK for up to 10 years if fertilization and water needs are taken care of. You should have enough chilling, 400 hours is needed, if you do not plant too deep. Al

Hi, when the tag says it needs "full sun"
does it mean it needs to get sun all day long like roses. Is it going to burn in CA summer if it gets too much sun?

When you grow a peony in a pot, do you leave it outside all winter long in the pot?

PoorOwner you don't say where you are in northern California, which has a range of climates. Full sun means full sun just like the roses. Just like roses without enough sun you will not have as good a bloom. If you keep the container well watered sunburn should not be a problem. Most of northern California will not freeze hard enough to break pots or damage peonies. If the winter is not cold enough to cause the stems to die back cut them down by the middle of Decmber. Al