They take Ls.
All jokes aside, apart from changing your diet and routine, a test base (slightly above TRT dosage, about 200mg max) with 40mg TBOL or even LGD @ 5/10mg will produce gains above what you can achieve naturally without making you look suspiciously big. However they will not make you achieve the look that i suspect you want.
However based on the fact that you are asking this question i can make 3 assumptions:
You are quite young (based on the fact that you care whether or not people think you are taking steroids), in which case, you shouldn't be taking them at all.
You don't know what you are doing because if you did, you would already know the answer to this question.
The look that you are trying to achieve is beyond what you can achieve without courting suspicion and you may as well just bite the bullet.
Very hard to do any more than assume without you providing your height, weight, bf % and lifts tbh.
Fake nattys come in all shapes and sizes, so on that front your question is not only vague but also confusing because who the fuck wants to be a beta cunt like that.