Is it possible to configure the AWS X-Ray retention period?

The retention period cannot be changed. X-Ray charges based on the number of traces, so the retention period does not affect the usage fee.

https://aws.amazon.com/xray/pricing/ per this URL, it is clear that "You pay only for what you use, based on the number of traces recorded, retrieved, and scanned."

You're not going to save anything by reducing the days of retention and also the default is 30 days.