Red thread is a fairly common lawn disease that usually doesn’t kill the lawn. It’s name comes from the red thread-like sclerotia that comes off the grass tips.
Similar to lawn rust the treatment plan is generally an application of fertilizer to help the lawn outgrow the disease. Try to keep watering to a minimum to allow the grass to dry off.
In general it’s not necessary to apply any fungicide. Because red thread isn’t likely to kill your lawn, applying fungicides is overkill when a fertilizer app would do fine.