Yes you can do that by changing some code. Open file ../wp-content/plugins/wpdatatables/source/class.wpdatatable.php and around line 3315 you will find this:

'orientation' => 'portrait',

Just replace it with this:

'orientation' => 'landscape',
New Version of wpDataTables - WordPress Table Plugin

New wpDataTables 6.2 Version

Folders/Categories for tables and charts, WCAG compatibility, New global time format with seconds, and more.