This page consists of screenshots from the Contact Form Design – Success Message Screen in Coming Soon Booster WordPress Plugin.
This gives an idea about how to configure Success Message Settings. You can easily customize the success message which has to be displayed to the users, when they successfully fill up the contact form.
Using Success Message Settings, you can provide content for Success Message which you would like to display when user successfully submits the contact form. You can also customize the Font Color, Font Size and Font Family for the success message.