To obtain the Going Viral side quest, interact with Amanda’s phone on the counter in the Lotusville Re-Aging Clinic in Hollywood Boulevard after completing the game. For this quest, you’ll need to head over to the western side of Hollywood Boulevard to find her by the Los Angeles Tattoo behind the seating area.
Speak with her then turn around and interact with the set up to activate the cameras. Afterwards, you’ll need to take out a bunch of named enemies all along the red carpet. Once you’ve taken care of them all, It’ll then be time for the last boss. Defeat her as well then loot the Sorry journal from where she fall. Lastly, make your way back to Amanda’s laptop where you turned on the cameras.
Once you do, the quest will complete!