Hello,
Actually, the contact section has been managed through contact template page. So, to add the desired text, you have to override the template page.
Also, to override the template page, please copy the ‘page template’ folder from the theme and paste it on your child theme then edit contact-us.php file located in ‘page template’ folder to add your desired text.
If you have any queries/confusions further, let us know.
Thank you.