WordPress recommends PHP version 7.4 at the time of writing. If you see an alert on your dashboard that the the website is running an insecure version of PHP thenyou have three options.
1) You can often update your PHP version in cPanel if you are comfortable doing that.
2) Ask me to update it if I have access to your cPanel.
3) Contact catalyst2 (link below) and ask if the latest version can be installed on your website. Then check the website is ok after they have done that (they usually do that also). Raise a ticket here: