If you are getting a notification in your WordPress dashboard that your site is running an older version of PHP in the Site health status corner. So .you need to update PHP to latest version.If your site has latest PHP version you’ll see like image below in your dashboard . Php info site
How to update php wordpress
How to update php version in wordpress site
If not then follow these steps to update PHP version of your website :
Step2:Login to the host site and go to H/C panel .
Step 3: Now go to the advanced setting or find option PHP configuration .
Step 5:Click on the PHP configuration and you can select the latest version for your website .