The PaymentIntent.create/2 function takes extra stripe options as second parameter. You can provide a keyword list with headers as key and a map as value.
The opts are passed to the new_request/2 function: stripity-stripe/lib/stripe/request.ex at dd89df648456f97e667938bed0e18550427c6a04 · beam-community/stripity-stripe · GitHub
opts = [headers: %{"Stripe-Account" => connected_stripe_account_id}]
PaymentIntent.create(params, opts)
