Hi @Raul Guchinife,
Just to clarify in advance, the Client Access role in Exchange 2016 and Exchange 2019 has been integrated with the Mailbox server role and does not need to be installed separately.
You can add new servers to an existing organization to deploy a hybrid environment.
Please check out the two articles below: Installing Exchange Server 2016 into an Existing Organization.
How to Configure Client Access Services on Exchange Server 2016 or 2019?
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