X-ray won't help.
It only shows the bone and that is unlikely to be the issue:
not enough of a hit to cause a fracture
Movement generally is NOT affected nor range of motion per se
The only thing that an x-ray MIGHT be helpful is if a
bone chip were knocked into the joint.
ON the Other Hand.... if a tendon or
cartilage edge were involved they WILL show up on an
MRI.
A tendon that is bruised is not a big deal, gets better with rest, anti-inflammatories, maybe an ace wrap.
If carilage is injured, damaged, or a part broken off, surgery is helpful and the knee is truly damaged.
Cannot say in your particular case. Exam would sort it out (if tendon sore to touch, if the support/movement of the joint is no longer normal, if there is still a lot of effusion, if there are awful clicks inside the knee when it is moved... all exam findings of considerable value).
So... NO on x-ray.
Yes on evaluation (possibly after a couple days of resting to see if everything gets better)