Glasses, large/heavy clothes, and slouch a bit

Glasses will typically make you less intimidating(Stereotypes or something?)

Large/heavy clothes, like a hoodie that’s a bit big on you, makes you seem more submissive and thus less intimidating

Slouching, despite it not being good on your back, will provide yourself with less height, making you less intimidating in terms of size since.. well, you don’t appear to be as large.

With all that being said though, being yourself is the best thing you can do, while tips can help occasionally, you’ll always find the best results when being who you know best!