After enabling the lifecycle rule, start tracking to which tiers objects are moved. AWS offers S3 Inventory as a tool that allows you to see the tier of each object. Other FinOps tools can also be used to obtain this information. Additionally, the CUR (cost and usage file) that AWS provides will not tell you which objects are in which tier but what cost is associated with what tier. This means that indirectly, you will also be able to get this information.