The Parent Record (Account) Related List (Contact Record) was Display on the Child Record(Opportunity).
- Click the setup and Click on Edit Page
- Drag and Drop the Related List–Single from the Lightning Components Option
- Edit the Page Label
- Choose the Parent Name (Account Name)
- Select the parent record Related List
- Choose the Related List type for Enhanced List
- Click Save and Activated
- Choose the ORG DEFAULT and click on Assign as Org Default
- Select the Desktop and Phone and click on Next
- Finally Click the Save and Use Successfully.