Currently, the defaults for existingRealmFileBehavior actually break "offline-first" functionality when using sync. I propose we update the defaults to the following:

              existingRealmFileBehavior: {
                type: OpenRealmBehaviorType.DownloadBeforeOpen,
                timeOut: 1000,
                timeOutBehavior: OpenRealmTimeOutBehavior.OpenLocalRealm,
              },

This would ensure that if the network is unavailable (which is generally not the case) that there is only a latency of 1 second before the local Realm is opened.