Fred Hechinger was 20 in Fear Street: 1978 when he played the character 'Simon Kalivoda (archive footage)'.
That was over 3 years ago in 2021.
Today he is 24, and has starred in 18 movies in total, 5 of those since Fear Street: 1978 was released.
In Fear Street: 1978, I think Fred Hechinger looks: