Q.Waterlogged peony
My peony was planted almost a year ago. We’ve had an unusual amount of rain this winter and it looks pretty bad. The leaves have turned from green to yellow and now brown. Should I trim the whole thing down? If so, is there a special way to do this?

Poorly draining soil; out of your control is very difficult for plants and trees.
I would remove any dead foliage and pull away any mulch material to aid in allowing soil to dry out.
You could try to lift the Peony if you feel this is the only way to save the plants.
You could pot them up or transplant them.
Remember that any time you move Peony you are restarting their clock and rebloom may take years.
I certainly understand the frustration when dealing with Mother Nature and so much out of a gardeners control.
Much will depend on how fast the water drains.
Not only the cost but the time and care that goes into our gardens!
I do try to remind myself and I will pass it on-'a loss in the garden makes for new opportunities'
Here are some links with more information that may help.
https://www.gardeningknowhow.com/plant-problems/environmental/flood-damage-garden.htm
https://www.gardeningknowhow.com/ornamental/flowers/peony/growing-peony-in-container.htm
https://www.gardeningknowhow.com/ornamental/flowers/peony/peony-care.htm