How can I modify the post-checkout shipping page?

Hello!
I’d like to add information on the shipping page that follows the checkout page, however I haven’t found a way to make changes using the standard shopify methods. Most likely you need to do this through code. Does anyone know how this can be done?
Ideally, I would like to make a checkbox with the consent of the conditions for international delivery, without which the “Next” button will not work, but if this is not possible, then at least just insert informational text.

I want to insert informational text before the “continue to payment” button where it is marked with a red zone.