aarife EP doesn't have a dependency to the October 2023 SU release. We've addressed an issue by making an adjustment to the EP enabling script (https://microsoft.github.io/CSS-Exchange/Security/ExchangeExtendedProtectionManagement/).
However, as you have not had EP enabled before, I'd recommend to install the update, make sure that everything works as expected and then switch on EP.
FranManuel86 that's correct. You need to add all the domains which are used in user forests where user resides who have a mailbox on Exchange Server which is running in the resource forest. If you miss to add a domain, users who are using this domain will not be able to change their password via OWA in case that it has already expired (as described in the KB).
JS2022 can you tell me which Windows Server version do you run?