Sims, 22, has three assists in 27 appearances for Southampton, with matches coming in the Europa League, Premier League, FA Cup and EFL Cup.
He’s also featured on loan for Reading FC in the Championship and appeared for England at various youth national team levels, earning eight caps with their U-20s. For Reading, Sims had three assists in 18 matches.
The Red Bulls have a history of signing English players, with none more famous than striker Bradley Wright-Phillips, the owner of 117 goals across the MLS playoffs and regular season. Others include winger Lloyd Sam, forward Luke Rodgers and winger Shaun Wright-Phillips.
The Red Bulls have one international roster spot open, though all 30 roster slots are currently filled. They could alleviate that issue by sending a player out on loan.