Although Sheldon is typically seen as a more stoic character on The Big Bang Theory (aside from his recent proposal), the move to his early years in Young Sheldon (along with the omission of traditional sitcom tropes like the laugh track) has allowed Armitage to deliver an incredibly moving performance that has impacted Jim Parsons in a major way.
Based on Jim Parsons’ comments to EW about his experience watching Iain Armitage perform as Sheldon Cooper, it sounds like he has nothing but good things to say about the young actor’s version of his decade-old character.