As far as I know, most RPG system requires many out-of-character interactions.
D&D (or other similar combat-oriented RPGs) imply a lot of rolling, tracking numbers, and declaring actions that don't really narratively describe what the PC is doing (e.g. "I use my bonus action for...", "I prepare the spell...", etc.)
Fate (and other narrative-oriented RPGs) also require a lot of out-of-character interactions, such as invoking or creating aspects.
From the definition for role-playing game on Wikipedia it would seem that some of those out-of-character interactions.:
A role-playing game (sometimes spelled roleplaying game and abbreviated to RPG) is a game in which players assume the roles of characters in a fictional setting. Players take responsibility for acting out these roles within a narrative, either through literal acting or through a process of structured decision-making of character development. Actions taken within many games succeed or fail according to a formal system of rules and guidelines.
That would be because at first it'd seem like that formal system of rules require doing some action that characters don't directly do.
My question is:
How could a game be an RPG (as described by the Wikipedia) while keeping out-of-character interactions from players at the minimum?
I'd like to center the question around the mechanics needed for fullfiling the definition that would require the least out-of-character interactions.
For this question, I'm defining in-character as when players describe what actions the character is doing in a narrative way (as would be done in a book).
Also, note that the question centers around players being out-of-character. It wouldn't matter much for this question whether the GM acts in-character or out-of-character.
