It's okay for your people to live in the real world; you can say Dave drives a Mercedes, and Linda eats precisely two double stuff Oreos every night, and Alice wears only bespoke (Italian) Brioni men's suits at work (a very high end brand, in the five figures per suit, custom cut and fitted for each body).
Mentioning brands is not prohibited; but obviously slander or false statements about the company can get you into trouble. Like, don't claim the Oreos were poisoned or caused cancer.
Being specific about brands can enhance your story, but don't forget brands get outdated as well. Some decades from now, My Little Pony or Paw Patrol may be outdated and not something readers will recognize. Also, the reputation of brands can change dramatically -- a brand considered innovative and cutting edge in one year may be considered worthless crap just a few years later, surpassed by their competition.
Brands (and famous personalities) naturally rise and fall and become ancient history. A lot of young people today may not know what the "pet rock" craze was about.
Be judicious in choosing which brands you mention; you don't want your work to be outdated in ten years.
