As LankaHost using CloudLinux, You can change PHP version of your cPanel hosting account anytime from your cPanel login.
In most of our servers, following PHP versions are available 5,6, 7.0, 7.1, 7.2, 7.3, 7.4, 8.0 and 8.1
In order to change the cPanel version of your hosting account, please see the instructions in following knowledgebase article
https://support.lankahost.net/Knowledgebase/Article/View/41/1/how-to-change-cpanel-php-version