Generally: depends. Remember, people on this site are here because they want/plan to die. Most of them have not had good experiences with professional help. The people who got better will probably not hang out on suicide forums that much.
There are people who say that they got "cured" out of depression and suicidal thoughts. I would say it's unlikely to be 100% "cured", especially if your problems have been going on for many years BUT your life can improve to the point where it's worth the struggle. I think the aim of "recovery" is not always getting perfectly fine, but just making your life less miserable piece by piece, eventually even good. Anecdotal evidence here but I have a friend who after getting proper medication stopped being suicidal (she was for many years), still gets depressive episodes but they're easier to deal with, I know therapy also helped. I know she hasn't been suicidal for a few years now.
Did it help me personally: yes, but to what degree - that's something I cannot tell for sure. I also avoided "professional help" for many years (for many reasons) but decided to see a psychiatrist and try medications because my friend/girlfriend? (complicated situation) at the time insisted on it. I wanted to do it only to make my death easier to deal with, so they could see that "I tried getting help" at least, but I planned to ctb during the next few weeks. Actually the meds I got made me feel so good for a few weeks that I decided not to kill myself lol. Now that idea keeps coming back to me sometimes but I am not 100% sure if that's what I want (I was 99% sure before) and generally speaking I'm trying to live, not just rot in bed.
So medications *were* a big game changer for me. Therapy not so much at first, but it slowly helped me deal with my life better and survive difficult circumstances that came later. Tbh I have been seeing my therapist for over a year and I feel like only since a few weeks I actually started "proper" therapy because earlier it was all about surviving an outside-circumstances situation where way too much responsibility was put on me. However I feel like it is helping, I found a good therapist, at least a good match for me (she respects the fact that I might choose to die so I can talk to her about being suicidal very openly) (idk if that's very professional of her but I don't care, it helped me a lot actually).
I would say it's worth trying if you can. Especially if you have someone in your life who cares about youn- even if you don't get better and end up dead, they may have an easier time dealing with it. Try talking to a therapist/psychologist, but just know that not every person will be a good match for you and it's a bit of hit or miss. Try seeing a psychiatrist and get medications, BUT before you start taking it - please, please research the substance you've been prescribed to know if it's the right choice for you (the first medication I got would either not work or harm me more, but luckily I researched it and didn't even start; ane the second med I got, and actually started taking, worked well for me).
Sorry for the long post but I wanted to include way too much I guess. I hope you will be able to get something out of it.
Good luck