The way to update the PHP version is to login at your web hosting vendor, and browse around the Control Panel to find out where they allow PHP versions to be changed. My favorite web hosting company is ionos.com and when I login the first click is on: Hosting
Next, I select which hosting package, because I’m a web developer I do hosting for several clients:
In the control panel I select: PHP
Finally, I select which domain should have a PHP version updated.
It’s a best practice to keep your PHP version updated to the latest supported version in order to get the best performance and security benefits. Older versions of PHP are being phased out, and a CMS like WordPress will simply alert you when your PHP version is too old.