1- You are only expected to follow my instructions only. (okay)
2- You are only expect to follow my instructions only. (wrong)
3- You are only expects to follow my instructions only. (wrong)
I've re-stated your examples using the verb "expect" instead of "subject".
Only 1- is correct. The presence in your examples of the verb "are" followed by another verb is an indication that the sentence is in the 'passive voice'. Passives usually have the verb "be" followed by a past participle. That means the correct verb must be the past participle "expected".
Also, it would be better to put the focusing adverb "only" at the end of the sentence to emphasise the fact that it is "my instructions", and no one else's, that must be followed. (You could also put "only" after the word "follow" if you preferred; the effect would be the same).