When an army soldier befriends the very Indians he is commissioned to fight, he discovers for the first time, who he truly is.
I agree that his need / goal should be objective (but possibly hinting at his subjective need), I don’t think you need ‘very’ and I’d consider changing ‘Indians’ to ‘American Indians’ or similar – as there is some discussion around the correct modern term for the indigenous peoples of the US: https://en.wikipedia.org/wiki/Native_Americans_in_the_United_States#Terminology_differences. Other than the fact that he’s supposed to fight them, I’m not sure what the soldier’s conflict is from the logline.
“Discovering who he truly is” relates to the character’s subjective need; it is an unintended consequence of the action of the story. However, loglines are not about unintended discoveries or subjective needs. Loglines are about objective wants, about a protagonist’s intentional actions to attain a specific goal.
For your consideration: a discussion thread of “Dances with Wolves” from last year.