free-shipping-based-cart-price.php

<?php

add_filter( 'woocommerce_package_rates', 'musilda_cart_price_free_shipping', 10, 2 );
function musilda_cart_price_free_shipping( $rates, $package ) {
        if( 1000 < WC()->cart->get_displayed_subtotal() ) { 
                foreach($rates as $key => $item){
                    $rates[$key]->cost  = 0;
                    $rates[$key]->tax   = 0;
                    $rates[$key]->taxes = false;
                }
        }
       return $rates;
}