Missing file sharing option in iTunes

Which sharing mechanism do you mean?:

1. Home Sharing controlled via the File > Home Sharing menu which will likely only be available if your are signed into your Apple ID and your computer is authorized for it.
2. Sharing, controlled from Edit > Preferences > Sharing, optionally blocked from the Restrictions tab.
3. File Sharing described in Use iTunes to share files between your computer and your iOS or iPadOS device - Apple Support. An older way to copy data to and from apps with iTunes. Apple recommends using the Files app with iCloud Drive, OneDrive, Dropbox, etc. if possible.

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