Yeah, announcing you were going to delete emails unread and expecting the sender to resend when you return would NEVER fly in my office. I’d get executive complaints about that, especially if it went to a client or outside party – if a client can’t reach you, they will reach out to someone else who may not work at your organization and you lose business. I feel like this delete-it-all philosophy would only work for an entirely internal role where timelines are more relaxed, and even then, I feel it’s a bit unprofessional to foist your own catch-up work onto others, especially if they’ve been backfilling for you while you were OOO.
Setting up an effective out-of-office autoresponder may seem to be a simple task. However, there is nothing worse than receiving an automated response that is not clear or useful. You want your “out of office” message to provide useful information and clarify why you are not available now. You certainly want to avoid any confusion or frustration.

These messages are useful at virtual Christmas parties, and to include on a virtual holiday party invitation.
I had a coworker that (pre-covid) had an out of office set up any time she worked from home. She didn’t operate any differently than when she was in the office, and there wasn’t any information in the message, just “FYI I’m wfh today”. It was weird to keep getting those messages, since her working from home had zero effect on your correspondence with her.