As others have suggested, content wise, probably not a problem. Pink does an AMAZING concert. I took my oldest daughter and a friend of hers a couple of years ago, and they had a great time.
Where we were the sound was not deafening, though obviously some areas might be so yes on the ear plugs (better safe than sorry).
But this largely depends on the child. My almost 7 yr old nephew is not used to confined spaces (concerts, movie theaters, etc), so he would likely not do well if he could not run around. My daughters at 6 would have been better prepared and more likely to enjoy.
It is definitely a late night. I do not recall when the concert let out, but it was late. Maybe leave the grandchild at home and just go enjoy it yourself.
(My daughter and her friend did not need a chaperone, but I wanted to go see the concert myself.)
I agree with all of this. Is your granddaughter going to be able to stay engaged and interested through a multl-hour concert (especially if it’s hard for her to see the stage)? Are you prepared for dealing with “adult behavior” going on around you, and for not letting your granddaughter’s presence disrupt the evening for the people seated around you?
I think a lot of this comes down to having a good, realistic understanding of your granddaughter’s strengths and limitations.