It’s important that you are aware that legally there are two types of complaints an employee can make to HR or to higher management – (1) complaints that are considered “protected activities” and (2) other kinds of complaints that are not considered protected activities.
A complaint is a protected activity – i.e. it provides the so-called anti-retaliation protection – if it involves complaining in good faith about unlawful discrimination, unlawful harassment, safety violations, and violations of specific other laws. “In good faith” means that you don’t have to be 100% correct in your allegations in the complaint you are making, but you have to be truthful and you have to have some legitimate basis for complaining, beyond your mere speculation that some kind of unlawful activity by your manager is at play.
For instance, complaining to hr about your boss giving you a hard time about your requests for accommodations to your disability, or about your workers comp claim, or using racist language toward you, or suggesting that it’s time for you to retire (age discrimination) etc., would be a protected activity. This doesn’t meant that the employer cannot fire you for this. They can still choose to violate the law and retaliate, but in that case – you will likely have a legitimate case against the employer (many other facts of your employment and termination will determine whether there is in fact a case worth pursuing).
On the other hand, if you complain to HR or your higher management about your boss micromanaging you, or not being nice to you, or issuing an unfair performance review to you, or bullying you this would not be a protected activity. Thus, even if you very clearly can prove that you were terminated for making that type of complaint, that would not give rise to any kind of retaliation or wrongful termination case.
If you are not sure whether your potential complaint would qualify as a “protected activity” under the law and you are concerned about retaliation, you should consult with an experienced employment attorney to discuss the same and also get help with drafting a complaint in a way that would be most effective legally and practically.