Custom Login Page v 5.0.x

Recently upgraded from 4.x to 5.0.13. Implemented ADFS Authentication which works w/o issue. When logging out, I am redirected to the /login. Would like to add a button to use ADFS authentication AND have the existing button “login” (type:submit) available. Can’t seem to find any information outside of branding the login page with version 5.x.