Prevent/Disable Automatic Update Check

How to disable core auto updates but enable plugins and themes auto
updates

If you want to stop the autoupdates of the WordPress core, but to
enable them for your Plugins and/or Themes, you can add these lines in
the wp-config.php file: Stop the core auto updates:

define( 'WP_AUTO_UPDATE_CORE', false );

Then Enable the plugins/themes:

add_filter( 'auto_update_plugin', '__return_true' );
add_filter( 'auto_update_theme', '__return_true' );

How to completely disable the WordPress auto updates

If you want to disable the WordPress auto updates completely, open the
wp-config.php file and add this line to it:

define( 'AUTOMATIC_UPDATER_DISABLED', true );