If using Windows 11 on a PC, can the flashcards created on the desktop PC be synced with the mobile App version on an iPhone?
Yes. If you create an account on AnkiWeb, you can sync additions and changes made on one device (for example, your Windows PC) to the AnkiWeb server. Then, you can sync those additions and changes from the AnkiWeb server to a different device (for example, your iPhone). Syncing works similarly in the other direction as well. This AnkiWeb syncing service is free.
You can read more about the syncing process in the Anki documentation.