Hello,
1) If you want to add any content before/after the cart/checkout form you need to edit the page. If you use Elementor as the main page builder then using Elementor, if WPBakery – WPBakery.
2) Font size of the elements on the checkout page could be changed only by additional CSS customization. You can use Theme Options > Custom CSS for these purposes or Yellow Pencil plugin.
3) Yes, banner to that area you can add using Static Blocks.
4) Edit the cart/Checkout page and choose the Breadcrumbs Style > Disable http://prntscr.com/tnz2i3 or add the custom CSS
.cart-checkout-nav {
display: none;
}
5)
is it possible to make this section wider https://prnt.sc/tnux98
Nope, there is no such option. It’s possible only by additional PHP customization if you have appropriate skills.
Regards