some.js

// in Cypress commands.js

Cypress.Commands.add('getStripeElement', (selector, value) => {
    cy.get('iframe')
      .should((iframe) => expect(iframe.contents().find(selector)).to.exist)
      .then((iframe) => cy.wrap(iframe.contents().find(selector)))
      .within((input) => {
        cy.wrap(input).should('not.be.disabled').clear().type(value)
      })
  })

// in your test

cy.getStripeElement("#Field-numberInput", "4242424242424242");
cy.getStripeElement("#Field-expiryInput", "1025");
cy.getStripeElement("#Field-cvcInput", "123");