Rewards update includes a new feature - assign VIP Tier by Tag.

For entrance criteria, you can select the Customer tag, then customers will automatically be assigned to the eligible tier if he has the tag.

Additional info: If a user has more than one tag suitable for different tiers, then we assign the tier that was created earlier. In the admin panel, we restrict the adding tags(option) on the achieving tier, and it is impossible to add the same tag from eligibility settings.