The dominant Formula Regional Americas title helps propel Linus into the last rung on the Road to Indy ladder in 2021, as he joins the Indy Lights Presented by Cooper Tires championship on the INDYCAR support bill. Once again, Linus is instantly on the pace, winning the very first race of the year at Barber Motorsports Park and finishing third overall in the final standings (as the top non-American). He is part of the Global Racing Group with HMD Motorsports operation.

Throughout the season, he wins a further two times – once at the hallowed grounds of Indianapolis Motor Speedway, and once in a commanding wet-weather performance in the last race of the campaign at Mid-Ohio.

At the end of the year, the top three Indy Lights drivers are awarded an NTT INDYCAR SERIES test. Linus grabs the opportunity with both hands on a successful first outing at Indianapolis Motor Speedway on November 1, driving for Andretti Autosport.