I have autoscaling group with max 2 value for the 1 instance launch i want attached elastic ip & for other newly launch server normal public ip how to do it

To set up an Auto Scaling group where one instance has an Elastic IP (EIP) and other instances have regular public IPs, you'll need to implement a combination of approaches:

1. For the instance that needs an Elastic IP:

• Create a launch template that includes your application requirements
• Set your Auto Scaling group's minimum size to 1 to ensure at least one instance is always running
• After the first instance launches, you can attach the Elastic IP to it using the AWS CLI command:

aws autoscaling attach-instances --instance-ids i-yourinstanceid --auto-scaling-group-name your-asg-name

• Then associate your Elastic IP with this specific instance

2. For additional instances that should have regular public IPs:

• Configure your launch template or configuration to assign public IPs automatically
• When the Auto Scaling group scales out beyond the first instance, these new instances will receive regular public IPs

3. To maintain this setup during scaling events:

• You can implement a lifecycle hook or user data script that checks if an instance is the first one in the group
• If it's not the first instance, it proceeds normally with a regular public IP
• You may need to implement instance protection for your EIP-attached instance to prevent it from being terminated during scale-in events

This approach allows you to have one instance with a static Elastic IP for services that require a consistent address, while allowing other instances to use regular public IPs for general scaling.
Sources
Detach or attach instances from your Amazon EC2 Auto Scaling group - Amazon EC2 Auto Scaling
Use CreateAutoScalingGroup with an AWS SDK or CLI - Amazon EC2 Auto Scaling