Yes, Nikki Giovanni once said that writers don’t write from experience; they write from empathy.
If you’re going to write about a subject you haven’t personally experienced directly (through yourself or through family/friends), the most important tool to possess is empathy. You need to feel an emotional connection with the subject and you need to identify with the emotions that are connected to the topic.
Then you write with those emotions. For example, without even personally experiencing sexual assault, you can already list some of the emotions that relate to it-fear, anger, sadness, shock, since you know how awful sexual assault would be because of what you learned about it naturally. If you can understand those feelings, you have empathy towards the subject.
If you have the empathy but you know little about the subject itself, then you need to do your research. For example, if you want to write about bipolar disorder and you have very little knowledge about the disorder, then you need to look it up and discover its main points and its symptoms and characteristics. You need to gain as much knowledge about the topic as you can.
If you have empathy and knowledge of the subject, chances are you will do it justice. Just be careful.