I addressed this general question in a paper I did back in my grad school days.
1) Can one be oppressed and not know it? Well, if not, then there wouldn’t ever be any need to do consciousness-raising to encourage the oppressed to rise up against their oppressors. There would be no such thing as “false consciousness”, a Marxist term for thinking things are OK and reasonably fair when they aren’t. It’s actually difficult to successfully oppress people unless a large chunk of the oppressed accept the situation as inevitable. Reciprocally, I suppose, if a situation is inevitable, and can’t be resisted, some people may not see it as oppression but as a fact of life, like the weather.
2) If one can be oppressed and not know it, how the ^$!@@ does one come to know with any meaningful accuracy whether one is in fact oppressed? Marxism has no good answers for us there; they wrap it as a tautology: the working class has false consciousness if and when they do not realize they are oppressed by the ruling class, and accurate class consciousness when they do so realize; the correctness of the latter and the falseness of the latter lies in the inaccuracy of the concepts held as true by the latter. But sociological theories that assume people’s attitudes are entirely shaped by socialization (social determinism) can’t explain how an oppressed population can recognize their oppression, as the oppressors would be teaching them that how things are is how things are supposed to be.
**3) Radical feminism, explicitly, looks to emotionally-driven cognitive processes, a political epistemology ** you could call it, for recognizing when “how things are” is not how things ought to be, and for exploring how things could be different or better, etc. Emotional states are more typically allocated as personal problems, and dissatisfaction as the proper subject for therapy, not politics, but here, too, radical feminism explicitly upends that and says “the personal is political”. Essentially, you can’t oppress people and not make them psychologically distorted in the process. Victims are not happy people.
None of this rules out the possibility that person NOT part of an oppressed category can perceive oppression where one of its victims do not, and yes that does happen. Consider children who are abused by their parents. They may state that what is being done to them is appropriate and/or that they brought it on themselves.
But at the same time it’s arrogant of someone who has read some social theory to tell someone “you are oppressed” as if it is a subject that has already been given all the consideratio that it is due and a verdict reached and hey, this is just how it is, you’re oppressed. In fact, that’s a disempowering way to treat someone in and of itself! If you respect someone as a person, you owe it to them to listen to their story and their situation as they theorize it. (Yeah, including abused children). After all, the goal is communication and, presumably, seeing the apparently-oppressed person become more empowered. Consciousness-raising is not a lecture, it’s a dialog.