I have created a custom post type bl_properties.
I have created a taxonomy city.

Now I want my city archive page url will be like: example.com/custom-string/city/city-name/

Register Post type:

$args = array(
    'labels'             => $labels,
    'public'             => true,
    'publicly_queryable' => true,
    'show_ui'            => true,
    'show_in_menu'       => true,
    'query_var'          => true,
    'capability_type'    => 'post',
    'taxonomies'  => array( 'status', 'city', 'asset_type', 'appt_type' ),
    'has_archive'        => true,
    'hierarchical'       => true,
    'menu_position'      => 4,
    'supports'           => array( 'title', 'editor', 'author' ),
    'rewrite'            => array('slug' => 'custom-string')
);

Register Taxonomy:

register_taxonomy('city',array('bl_properties'), array(
        'hierarchical' => true,
        'labels' => $labels,
        'show_ui' => true,
        'show_in_rest' => true,
        'show_admin_column' => true,
        'has_archive'        => true,
        'query_var' => true
));

I have tried with category based permalink from WP-ADMIN area but not working for mu post type.