The breadcrumb can reduce the number of actions a visitor needs to take in order to navigate to a higher-level page, and improve the discoverability your store.

In Theme customize, go to the Product page > Default product > On the left sidebar, you guys will see the Breadcrumb option here:

Click on the Breadcrumb option, the right settings sidebar will show up. 

• Show breadcrumb checkbox: Tick/ Uncheck on this checkbox to enable/disable the breadcrumb.
• Show back/next product links checkbox: Tick on this checkbox to show previous/ next product if you open the single product page from a Collection page.

When you go to the Single product page via the Collection page, the previous/ next product option will show like the image below: