Prefill billing address data with custom adress array for guest

Hi all is there a way that i can pass custom billing address array to prefill billing address data on review and payment page

$csutomerAddress = [
‘firstname’ => “testname”
];

currently i have create created view model where i have this above address data array but i am not able to call it on checkout page.

anyone knows from where magento render billing address detail.

Thanks.