Olivia Rodrigo marked her 21st birthday by celebrating her final day of “hypothetically” underage drinking. The ‘Vampire’ singer celebrated her milestone age on Tuesday (20.02.24) and was joined by friends Iris Apatow, Conan Gray, Tate McRae and her rumoured new boyfriend The Kid Laroi for a party. She said alongside an Instagram post of photos of them together: “I’ll blow out the candles, happy birthday to me.” Olivia added: “Today is my last day of being able to underage drink (hypothetically)!!!!” She and her pals celebrated with a party at home, with Olivia wearing a black dress as her she…