Can we lock users out of Fusion HCM using Maintenance Mode?

We would like to lock end-users out of Fusion HCM during our Prod Redwood Migration. Is there a maintenance mode we can activate to accomplish this temporary lock out? We have Okta SSO enabled.

We have already enabled Redwood in a lower environment & thoroughly tested. We are planning on converting to Redwood in Production during business hours. We will send out a communication to users to not log in during the maintenance window, but we were wondering if we could temporarily lock them out in case they don't see or disregard the communication. We don't want end users to have a negative experience utilizing the system during a maintenance window.