"Career" and put it on Expert vocals. Then click on the Mall of Fame tour and play the microphone challenge at the bottom. (Audio-Technica Sponsor challenge) Pick "Grave of Opportunity" and simply shout random things into your microphone or blow into it and you will hit every note!
This exact approach can be done in GH5, too ^^ But instead of Grave of Opportunity
, you can choose On Broken Glass
This is not new to me
Other easy vox challenges are the SP% ones. I know one (or two) of the Taylor Swift songs is this; just do it on medium... if you capable