Q.What Type Hydrangeas Are These
Hi! These were here when I moved in and I’m afraid if I prune them back they will die. I would like to know how to care for these they’re in a very rocky area close to my house

The single one in the picture is most likely hydrangea macrophylla, also known as, Big Leaf Hydrangea, French Hydrangea, Hortensia, Lacecap Hydrangea or Mophead Hydrangea. Because it develops dormant spring 2023 flower buds at the end of the stems in the summer 2022, it is best not to prune the live stems of this type of hydrangea except to remove stems that do not leaf out by the end of May in the south, the end of June in the north and in July near Canada. However, it would be rare that severe stem pruning would kill the roots and therefore the plant. It is very common to hear of accidental pruning with mowers in which the plants eventually grew back after several growing seasons.
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/mophead-hydrangea-care.htm