These are the steps:
Find the Magento core form field Knockout template:
vendor/magento/module-ui/view/frontend/web/templates/form/field.html
Copy the file to your theme:
app/design/frontend/Inchoo/[Theme_Name]/Magento_Ui/web/templates/form/field.html
At the bottom of the file, create the Knockout if in order to check where you wish to add that custom text.
For example, if you wish to add something after the Last Name input, you will add this:
<!– ko if: element.inputName === ‘lastname’ –> <div class=”delivery-address-title”> <h6 translate=”Please add your delivery address below”></h6> </div> <!– /ko –>
Also, if you need to place that text (or some other piece of static content) somewhere else inside the Address form, you need to inspect the Knockout syntax and look for the inputName:
If for example you need a modification after the Zip Code, then your Knockout if statement will have code postcode instead of the lastname