how can i increase elastip ip quota by region

You can request a quota increase via the Service Quotas dashboard even with Basic Support. To view this, click on the top-right of your AWS console where your role is, and select "Service Quotas". From there, go to the left-navigation and choose AWS Services, then EC2. From there you should be able to find the applicable quota and request and increase.

A shortcut link specifically to Elastic IP quota can be found here (just be sure to select the correct AWS region in the region selector): https://console.aws.amazon.com/servicequotas/home/services/ec2/quotas/L-0263D0A3