How Do I Fix Dates on Photos My Family Sent Me?
Photos arriving by message or email usually have nothing left inside them. Here are the options.
Messaging apps strip metadata. A photo sent by WhatsApp, Messenger or iMessage arrives with no capture date and no location, so it lands in your library dated today.
Email is better. Photos attached to an email are usually sent as-is, so they often keep their original EXIF, including the date. It depends on the sender's mail app, but it is worth checking before assuming the worst.
For the ones with nothing left, setting a date for the whole batch is the practical answer. Takeout JSON Metadata Fixer can stamp a folder with a date and place you choose, so the photos sit roughly where they belong.