I wash most merino clothing by hand. Just washing in warm to hot water can shrink Merino wool. That's what I do if I want to only shrink it a little bit and/or control the shape as it dries. Google "wool dry block" which is where you can control the shape as it dries.
If an item is way too big, then I nuke it in the dryer. Of course, I check periodically to make sure it doesn't shrink to doll like sizes.