Currently we support 5.4, 5.6, 7.0, 7.1, 7.2 and 7.3 version of php. This can be easily changed in your dashboard. Please be aware that separate clusters are used for each php version and IP address of your hosting will change after changing the version. If you use Snackhost DNS this wont be a problem as internal DNS would adjust automatically but if you use foreign DNS you need to do the changes manually.
To change your DNS records you can use following link as a guide HERE
If you want to know what settings of php we use, check this page: