On a recent Saturday at an Ulta Beauty store in midtown Manhattan, Denise McCarthy, a mother in her 40s, stood in front of a wall of tiny pastel bottles, tubes and compacts. Her phone buzzed — another TikTok from her 15-year-old daughter. "My kids text me the TikToks," she told CNBC, scooping Korean lip tints and sunscreens into her basket, destined for Christmas stockings. "I don't even know what half of this does. I just buy the ones they send me." Two aisles over, a group of college students