How to select payin3 as default payment method using rest api in paypal - paypal

Question

I want if my customer clicks a customised payin3 button from my site he redirects to paypal page where payin3 should be selected rather than paypal balance by using rest apis what should I do?
Here is my code which is not achieving that requirements.
{
"intent":"CAPTURE",
"purchase_units":[
{
"reference_id":"58Y18137NX645002L",
"amount":{
"currency_code":"GBP",
"value":"120.00"
}
}
],
"payment_source":{
"paypal":{
"experience_context":{
"payment_method_preference":"IMMEDIATE_PAYMENT_REQUIRED",
"payment_method_selected":"PAYLATER",
"brand_name":"EXAMPLE INC",
"landing_page":"LOGIN",
"shipping_preference":"SET_PROVIDED_ADDRESS",
"user_action":"PAY_NOW",
"return_url":"https://example.com/returnUrl",
"cancel_url":"https://example.com/cancelUrl"
}
}
}
}

Answer 1

The necessary value is:
"payment_method_selected":"PAYPAL_PAY_LATER",
The behavior of the PayPal page after login may vary in sandbox, and in live according to whatever the signed-in payer account has available to it. Pay Later may or may not show and may or may not be the default, but as far as requesting it show if possible this parameter is all you need to do. There is nothing else.
Ultimately, the payer can always select a different funding source within a PayPal.com checkout, and all payments will look the same to the receiver account (simply a "PayPal" payment) whether or not Pay Later was actually used. Any use of Pay Later or PayPal Credit is between the payer and PayPal, and kept private the same as any other funding source selection (Balance, Card, Bank, whatever)