Is it reasonable to say in the store lease contract that "the fixed facilities added due to renovation shall be owned by the lessor free of charge"? What if it's unreasonable?

The agreement stipulates that everyone can accept it. Legally called surcharge. You can negotiate with each other. If negotiation fails, don't pretend. Otherwise, people have the right to sue you for infringement and restore the original appearance. If you can't demolish, or the demolition loss is great, and the value you pay is quite large, let the beneficiary make appropriate compensation.