How can I help a know it all 20 year old?

I have a step daughter, she is struggling with anxiety, depression and low self esteem. I have been trying to help her with coaching, we also just hang out and have fun together, we frequently have lunch and since learning about self coaching through Brooke, I have accepted her and not tried to change her anymore, and just love her, my feelings have changed around her, and I am grateful for the self- coaching that made that possible. She is 20. I continue to try different approaches to help her when we are together, I don’t feel the need to change her anymore, but I still find that I have a strong desire to want to ease her suffering if at all possible, since she does talk about her suffering a lot. Whenever I try to tell her anything, or coach her or make any suggestion for her to think about something differently or anything at all, she says she “already knows” and she is already doing that (whatever I suggest), or she already knows, she knows she knows, then she goes back to complaining that things are just hard for her, and everything is “just hard”. She will say, “Oh I know that already, but it’s just hard for me” I know that while she continues to think the thought “everything is hard”, that things will continue to be hard and her thoughts won’t change on their own. How can I best help her? Should I help her? Or should I just love her and listen? Is there anything further that I can actually do? Is it a waste of time to try to coach, help, suggest or anything more? Or is it best to just love and listen. As coaches how do you talk to people that are not coachable? Or do you still try to coach someone who does not want to be coached? Thanks!