Specific Shipping Method Based on Minimum Order Amount in WooCommerce

// =========================================================================
// MINIMUM ORDER AMOUNT FOR SPECIFIC SHIPPING METHOD
// =========================================================================
function minimum_order_amount_for_shipping( $rates, $package ) {
   $threshold = 100;
   if ( WC()->cart->subtotal < $threshold ) {
         unset( $rates['flat_rate:2'] );
   } 
   return $rates;
}
add_filter( 'woocommerce_package_rates', 'minimum_order_amount_for_shipping', 10, 2 );