Play? No.
Get a gist of? Helps a lot.
Plenty of YouTube runs of the first game's story. This is a direct sequel, and some events happened in the comic book series which has been reviewed quite well and has continued to be successful since the first game's debut. I do highly recommend, at the very least, exposing yourself to the first game's story before playing Injustice 2, even if it's not necessarily required to understand the INJ2 story itself -- it helps provide a lot of good context and I honestly think it's one of the more fun DC stories told in any medium, even if I have a hard time watching my boy Supes fall from grace so hard.