This block on product page helps you display bundle products. Customers can add multi-products to cart with just one click. You can check this feature on the demo link (pass: 4)
Steps: Go to Product page > Product main > Add block > Bundle product
Note: Products out-of-stock will not show in the bundle.
You can click on 'Select products' button to choose product lists. The list product here will show the same for all product pages.
If you want to choose different product lists for each product page, you can connect it with metafield "Complementary products".
Step 1: From Shopify Admin > Products > Open product you want to show bundle products > Choose some products in "Complementary products" metafield at the bottom of the page.
Step 2: Go to Theme customize > Product page > Bundle product > connect bundle product with the metafield.
Please follow this video to config it: