Hello!
All depends . Some get inspiration and ideas by their past , by what they went through.
Or just by looking someone , the past of someone , how they act … even if they don’t experienced this situation , just by knowing their story they can write a lyrics
Or sometimes by their feeling ( like love ) and they say what they do .. look at the person that they love , think of them all the time …
Some talk about their best friends or a heartbreak or a bad person
generally is always about the past or what people go through or went through
Hope it helps!
Bye and don’t forget I’m proud of you!<3