Q.Hydrangeas
O my hydrangeas, which bloomed prolifically this year, now look like this period they all had some fungal leaf damage , too.
Should they D cut back now ,And if , How far ?

Hydrangea pruning differs on the plant variety.
Since it is not clear what type of fungus that you are dealing with it is difficult for me to help you determine a treatment method.
Since you treated with a fungicide, you should likely wait out the results and health of the plants during this growing season.
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm