Navigate to the Shopify Admin Page -> Customize -> Theme Editor -> Theme Settings -> Product Page -> Custom Link on ATC Button
When this option is enabled, the ATC Button of the product you put a URL Link will redirect to that specific link
Other Useful Information:
Different Add To Cart Options - Change the General Add to Cart Button to different styles/ layout
Variant Swatch Style Options - Learn how to change the variants swatches to different styles.