Whatever you need when you meet all of the criteria for a purchase.
PayPal makes the PayPal Credit option available at timie of purchase when you qualify. So, maintain a credit score of 800 or more, no late payments ever, substantial financial assests, steady financial revenue, a house paid off, and more. Multiple credit cards with high avaiable balance would help.
I think you'll find that using it isn't so easy. It's not like a credit card which can generally be used up to the maximum. PayPa uses a variety of security and risk assessments for each purchase and PayPal Credit may not be availalable. when all factors are good you will be presented with a PayPal Credit option for selection. You can't change the way the system works.