Most games have a "preview" option, not all, but most. If you purchased the game instead of previewing it you cannot get a refund. All purchases from the Playstation Store are final.
You could call and plead your case to Customer Support (link to the phone number is in the bottom left corner of any forum page), but it seems this is generally a futile effort.
** Engage brain before putting mouth in gear ** ** two-step verification - use it **
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