Yes Its Possible Just Simply Run This Query Once
If You’re Not Developer Then Don’t to Anything
Just Simply log in to your cpanel->open phpmyadmin->There is maybe one or more database you’ve to find which one is wordpress database (click on database and where all table names starts with “wp_” its your WordPress Database -> and check there’s few tab “browse / structure /SQL” Go to SQL Paste this Code write below and click on go you’re done now.
UPDATE `wp_posts` SET `post_type`='page' WHERE `post_type`='post'