He attended McCutcheon High School and was ranked as one of the highest prospects in the state of Indiana.

[1] As part of his dominant senior journey, Phinisee was able to tie the all-time scoring record at McCutcheon (set in 2002 by Avery Sheets who went on to play at Butler) when he hit a 3-pointer at the buzzer to end the first quarter in the game against Harrison on December 15, 2017.

[2] On February 16, 2018 Phinisee and his teammates clinched the North Central Conference title (eventually going 9–0).

[3] The season came to an early close with a loss against Zionsville's Eagles, 50–60, leaving the Mavericks with an overall record of 20–5.

[10] On January 20, 2022, he scored a career-high 20 points including the go-ahead 3-pointer with 16.5 seconds left in a 68-65 victory over Purdue.

His skills and abilities led him to a spot on Indiana Elite's AAU team.