Reduce size of responsive title

You can add custom CSS where you use media query in order to reduce the font-size of the title in small devices. You also have some styling that remove the line break and add the 3 dots at the end. So you can also remove them.

You can try this code :

@media all and (max-width:480px) {
  .woocommerce div.product .product_title {
    font-size:18px;
    white-space: initial;
    text-overflow: initial;
  }
}

You may adjust the value of font-size as you need.