Trying to redirect to checkout only if the product has a "Trial" category.

example.php

add_filter( 'woocommerce_add_to_cart_redirect', 'example_redirect_to_checkout' );
function example_redirect_to_checkout() {
    $redirect_url = WC()->cart->get_checkout_url();
    
    if ( is_product() && has_term( 'Trial', 'product_cat' ) ) {
        return $redirect_url;
    }
}

example2.php

add_action( 'wp', 'example_add_redirect' );
function example_add_redirect() {
    if ( is_product() && has_term( 'Trial', 'product_cat' ) ) {
        add_filter( 'woocommerce_add_to_cart_redirect', 'example_redirect_to_checkout' );
    }
}

function example_redirect_to_checkout() {
    $redirect_url = WC()->cart->get_checkout_url();
    return $redirect_url;
}