I have recently ran into an issue that I had to change the Magento 2’s default contact form for my websites due to google’s request.
I have found a lot of articles stating that the contact form will be among your blocks or pages. My contact form’s url is “contact” and I couldn’t find it in blocks nor in pages. I did some research and finally I figured that there was no option for me to change this from the back-end rather I had to go and look for a file that has this information on my server’s filesystem.
After some research I found that the file containing the Default Magento 2 contact form is called form.phtml and it is located in /vendor/magento/module-contact/view/frontend/templates/ directory on your server. You can add HTML code of your choice to this file, once updated it refreshes straight away even if you use extensive caching like I do.