You can specify lifetime for the session cookie using setting cookie_lifetime

When storing session in for instance Redis using Ibexa\Bundle\Core\Session\Handler\NativeSessionHandler, the item will get a TTL in redis. However, PHP will use the php.ini setting session.gc_maxlifetime when setting that TTL value. So there is no connection between the cookie_lifetime and that Redis TTL.

The NativeSessionHandler only have options to manipulate the php.ini settings session.save_path and session.save_handler. It also needs to be able to manipulate session.gc_maxlifetime