IOPS Increase on EBS GP3 volume

Yes, you can increase the IOPS and throughput without interrupting the running instance. Bsst practice is to take a snapshot before modification

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/requesting-ebs-volume-modifications.html#modify-ebs-volume

You can monitor the status of the modification as well. See https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/monitoring-volume-modifications.html