How to customize vendor view files?

In yii2 how do I customize vendor view files without modifying the original view files?

I'm using dektrium yii2-user and would like to make a few changes to the login page.

You can assign your view path for dektrium yii2-user in this way (assume @app your app alias) :

'components' => [
    'view' => [
        'theme' => [
            'pathMap' => [
                '@dektrium/user/views' => '@app/views/your_dir_views'  // mapping for override the views dektrium with  your views 
            ],
        ],
   .....
 ],