Hi @chenhui ,
With a single HA Pair you should be using FlashPool. FlashPool is what NetApp used to refer to as a Virtual Storage Tier (VST), but it is not the same as data tiering from other vendors. If you need more information on FlashPool then you should read TR-4070 https://www.netapp.com/pdf.html?item=/media/19681-tr-4070.pdf&v=20201013219
If you have a cluster of NetApp arrays then you can configure up FabricPool with local S3 bucket tiering "tier to local bucket". If you have an older NetApp array (that supports S3), StorageGRID, or cloud S3 target then you can use FabricPool which is a similar technology to other data tiering from other vendors.