things disappear when i get far 5/10 M + Trees get bugged in an odd way. Anyone can help with it?

i have uploaded

an image to describe better the problem, I have already tried in clippin plane of the camera setting up the far in many ways but it doesn’t change the problem. the problem is the render distance but i don’t know how to increase it. maybe it is an option in unity settings.
but really i can’t do anything…for example days ago i downloaded an asset from the store, it was rocks.
If i get far like 5 meters they disappear ! and i’m wondering if my eyes are seeing this for real or what, it never happened !
if anybody could help me it would be so nice !!!
Thanks for reading
Olly

Try to turn off Occlusion culling. I have seen many bugs with it (stuff beeing CLOSE to the camera disappearing,…) regarding this. If it indeed helps, you at least know where to start.