Sydney Sweeney took a big step in her relationship with Scooter Braun by spending time with his three children. Page Six obtained photos of the “Euphoria” alum and the music executive taking his kids, Jagger Joseph, 11, Levi Magnus, 9, and Hart Violet, 7, to grab smoothies in Los Angeles on Tuesday. Sweeney, who wore a casual white T-shirt, light blue jeans, white sneakers and black sunglasses, doted on her partner’s little ones. At one point, the “Housemaid” star wrapped her arms around one of Braun’s sons while they were inside Sunlife Organics. Sweeney also hugged two of the three kids as the group walked together in the parking lot….