We are familiar with salesforce classic, but after transitioning to lightning we missed some feature. One of the awesome feature is Child Related list quick links on record detail page. In classic we can easy to redirect to related lists records through this link. But in the lightning we are struggling to access the related list. Right now they are providing the gift for placing related list quick link on lightning page.

First, we will show you the steps as an Admin perspective to customize the page.
Step 1: Open any Detail record page – > Click On Setup-> Edit Page->

Step 2: The Page will look like below in the edit mode. Now go ahead on the left-hand side and see there is a lightning component named related list quick links we need to drag and drop the related list quick link component on immediately beneath the compact layout as shown in the screenshot.

Step 3: Click Save for the page – Now we can see accounts have a related list component with the link as shown in the below screen.

We will see a preview of all related list components after dropping the lightning component beneath the compact layout.

At this point, we are all set. To make this the most beneficial to our team it would be advisable to have only the Related Lists as Quick Links.

Then, where we need to have the actually Related List displayed on the Page, use the Single Related List component as a means of enhancing the experience.

We can simply hover on any of the related object links, it will show up to 10 items in the preview mode. From the hyperlink, you can redirect to any of the records.

Reference :

Related Lists on Records in Lightning Experience, Customize Related Lists