90's film... SOLVED: A Far Off Place (1993)
that takes place in a desert African setting.
I more or less just remember the preview for the film. I think it's about an American family in Africa, with a son and a young daughter. Seems like the boy has a strong bond with a lion and also has a strained relationship with his sister for some reason.
So the scene in question: Master shot of an African desert-like landscape (I'm sure there was long yellow grass). From the right of the screen, the boy is running, and then a mid shot of his sister noticing him and starts to run towards him with joy from the left side of the screen. As the cuts get shorter and shorter as the two run towards each other, the lion leaps into the boy's arms, and his sister seems disappointed/defeated emotionally.