You can log in to the VPC console and click IP And Network Card > ENI in the left-side directory to open the Elastic Network Interface list page.
Click the instance ID for which you want to request for a secondary private IP to open the details page.
Click the IPv4 Address Management tab, click Assign Private IP on the interface, select Automatically assign in the pop-up box, or manually fill in the private IP to be allocated.
Note:
If you choose to fill in manually, make sure that the private IP you fill in is within the subnet IP range and is not a system reserved IP.
For example, the subnet IP range is:10.0.0.0/24, then the available private IP range is:10.0.0.2 - 10.0.0.254.
