The surprising thing for most people about negotiating a lease? You need to negotiate the purchase price, not the monthly payment. Even though you’re leasing, it’s still the purchase price that determines your monthly payment.
Whether buying or leasing, many people fall into the trap of negotiating monthly payment. This is exactly what the dealer wants. Rule #1...The BOSS commands that you negotiate purchase price no matter how bad the dealer wants to negotiate monthly payment. You can easily research purchase price on websites like Edmunds and KBB. Rule #2...do not step foot in the dealership until you've done this research.
Here’s an example from KBB for a 2019 Toyota Camry SE:
KBB tells us that other buyers in our market have been able to negotiate a purchase price of about 10% off MSRP.
Check this LINK for an excellent article on negotiating purchase price with a dealer.