For asynchronous messages, the retention period is adjusted using properties xiadapter.inbound.persistDuration.default and xiadapter.outbound.persistDuration.default and the default value is one day.
For synchronous messages, that are persisted in the database, depends on the value configured in messaging.syncMessageRemover.messageCount.
You can also take a look at the KBA below. I provides more details about how messages are persisted:
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