If I pass a toll w a fox rental and I’m not from California, does Fox pay for the toll?

No, they will change you

You need to pay the toll yourself. If they will be forced to pay your toll you'll be charged the amount of toll plus extra fee.

You can buy a pass so that you can use them without worrying about it

They charge you $25 plus you have to pay for unpaid toll fees

You can also pay to have tolls taken out.