woocommerce-replace-add-to-cart.php

 // Replace the Add to Cart Btn in Category Firearms with Read More Btn

  add_filter('woocommerce_loop_add_to_cart_link','change_simple_shop_add_to_cart_btn',10,2);
  function change_simple_shop_add_to_cart_btn( $html, $product ){
      if( $product->is_type('simple')) {

       $category_name = $product->get_categories();
       

      if (strstr($category_name, 'Firearms')) { // your category name 'Firearms'

 $html = sprintf( '<a id="read-more-btn-fa" rel="nofollow" href="%s" data-product_id="%s"  class="button vp-btn">%s</a>',
                  esc_url( get_the_permalink() ),
                  esc_attr( $product->get_id() ),
                  esc_html(  __( 'Read More', 'woocommerce' ) )
          );
          $category_name = $product->get_categories();
      }
    }
      return $html;
  
      }