Mackenzie Shirilla is already thinking about life after prison ... and it sounds like she's got big plans for what might come next.

Take a listen ... TMZ obtained audio of Mackenzie chatting with her mom, Natalie, about  her future and a potential new purpose she sees for herself ... becoming a life coach.

Natalie tells her daughter she's been through an incredible amount and suggests those experiences could one day allow her to help others. Mackenzie, who is serving two concurrent sentences of 15 years to life, seems to embrace the idea.

The exchange is brief but revealing ... offering a glimpse into how Mackenzie is envisioning her future behind bars and the kind of impact she hopes to make if she's someday released.

This call is a change of pace from other's we've heard ... like Mackenzie chatting with her mom about boys she's talking to and how thinking about the fatal crash makes her want to puke.

Mackenzie remains incarcerated in Ohio following her 2023 conviction in the crash that killed Dominic Russo and Davion Flanagan, which prosecutors said was no accident. She's the subject of Netflix's hit documentary "The Crash," which has reignited public interest in her case and she's fighting her conviction and maintains she's innocent.