Users can request a copy of their personal data via User Settings > Privacy & Safety . However, this typically only includes messages that currently exist; manually deleted messages are usually excluded from these archives. Methods for Viewing Deleted Messages
For server owners, setup a dedicated logging channel immediately. recover-deleted-messages-on-discord
Bots like Dyno or MEE6 can be configured to log message events to a private moderator channel. Users can request a copy of their personal
Only use reputable bots from verified developers to log server activity. How to Prevent Future Loss recover-deleted-messages-on-discord