Relevant expressions include:
toe the line, toe the party line - expressive of conformity and a meek acceptance of authority
Radio stations are pretty much forced to toe the line since they rely
heavily on record companies for ad dollars and listener-grabbing perks
like contests, interviews and concerts.
(don't) make waves - don't cause a disturbance
Being part of the jeans generation is an affirmation of the positive
aspects of life, and indicates a willingness to defy convention and
question tradition, rather than keep a low profile and avoid making
(don't) rock the boat - don't disturb the status quo, upsetting everyone
They want to be sure that nobody rocks the boat and no major donors
(don't) stick your neck out - don't expose yourself to (social) danger by making yourself noticeable - this example also includes keep your head down, also potentially useful
You stuck your neck out when others kept their heads down and their
(don't) put your head over the parapet - similar to don't stick your neck out, but with more emphasis on risking upsetting someone
It is unfortunately not ‘politically correct’ in Wales to stick one’s
head above the parapet and voice these concerns as I am doing.
Example sentences are taken from the dictionary references given, except for the one immediately above which is from here.
As an alternative way of going about things, it seems to me that what you describe in your question does sound like quite a Japanese situation and the Japanese proverb, deru kugi (kui) wa utareru - commonly rendered in English language texts about Japan as the nail (stake) that sticks up/out is hammered down - does sound like a reasonable thing to refer to in this situation. It's far closer in spirit to what you ask for than any of the English idioms I can think of.
Edit: After posting I saw the comment by Andrew Leach, also referring to this Japanese expression.
(Side note: as you may come across this when doing your research, the kui/kugi thing is to do with construction techniques and a certain purism - traditional Chinese and Japanese building techniques don't use nails; wooden stakes 'lock' blocks together. Kui seems more common in online references, but I've only ever heard people say kugi ...and English renderings invariably go for nail, as it very sensibly sidesteps the need for just the kind of explanation I'm giving you now!)