You can do this by editing your Theme Language. Head over to Admin > Online Store > Themes > Action > ‘edit languages’ to add some additional text to the 'shipping method title:
Making edits here will show a note or message where the red line is below:
Is that what you’re looking for? Let me know if I missed the mark.
Adding notes to this section is a great way to communicate more specifically with your customers. It’s also recommended that you add any special instructions, notes or important details into a Shipping Policy page. You can learn more about that as well as access a free template and examples here.