For a $32 delivery order, the usual practice in the US is a tip of about 15% to 20% of the pre-tax food total, so roughly $5 to $6.50 on $32. Many people also add a few dollars more when the weather is bad, the order is large or heavy, or the building is hard to reach, and a driver who has to climb stairs or find a gate often earns it. If the delivery fee or a service fee is already on the bill, check whether the app has a separate tip line, since some apps pre-select a tip that may be low. Tipping in cash directly to the driver is also common, and it goes straight to them.
If you tell me your city or country, I can check whether local norms differ.
