How to change CIDR range of account created by Control Tower

According to https://docs.aws.amazon.com/controltower/latest/userguide/vpc-ct-cidr.html

If you change the CIDR range in the settings of Account Factory, all new accounts that are subsequently created by AWS Control Tower (using Account Factory) are assigned the new CIDR range. The old accounts are not updated. For example, you can create an account, then change the CIDR range and create a new account, and the VPCs allocated to those two accounts can be peered.

So it doesn't look like you can change the CIDR range of a VPC on-the-fly, you would have to delete one of the accounts with the overlapping CIDR range, then change the CIDR range in Account Factory, then re-create the account.