400mm vs 300mm

For you experienced shooters, what is your recommendation.

I shoot high school sports (all), and I am also allowed in the sidelines. Would a 300mm 2.8 be enough or would a 400mm 2.8 be better?

Ive talked to some photographers and seen they use the 200-400 f4 for night games but they use it on 1DX bodies. I use a D850 so i know i wont get the same low light capabilities as a sports camera (1dx or d5/d6) I will be pairing either with the 70-200 2.8 or 24-70

Edit: let me throw this lens as a contender 120-300mm 2.8.