Is it possible to change the height of the map in the contact page?

Never mind!

I just find it! I have to use a "Default Template" page for my Contact page instead of a "Contact Template" page.

And in the "Default Template" page, I simply add a Google map Element, and in this element I can control the map height.

So if you want to adjust the Contact Map Height, don't use the "Contact Template", but build a default page with a Google Map!