In my opinion, I have never noticed anything significant from taking a supplement. I think it is exactly what the name suggests, it is purely supplemental to your diet and exercise routine. There is no magical trick to being fit and lean, the answer is simply eating a healthy diet.
Personally, I take a daily fiber supplement to help with regularity, and two types of protein in powder form only after workouts or for meal replacements. I also take a hair vitamin supplement as well as pre-workout (only on heavy leg days- I don't think it is very good for you) and an L-Carnatine supplement occasionally in liquid form (it tastes good😊).
Although these are all great supplements, I don't rely on any of them to keep me in shape or healthy. The best results I have ever had come strictly from eating clean and being honest with myself about it. If you are not noticing results from your workout routine, then honestly ask yourself if you are eating a clean, healthy diet. Try to tweak it, or remove some things (personally, my body HATES sugar and alcohol, so I notice better results when I am not consuming too much of those things), and see if your physique and health improves!
I've listed links below to the supplements I take, just in case you are curious! Also, I would like to say that if you are taking a supplement that you feel is really effective, then that is great! If you feel that it is helping you and it is safe, keep at it!
Truvani Plant-based protein powder: https://bit.ly/3fmSSdE
1Up Nutrition whey protein powder: https://bit.ly/2SIixpw
1Up Nutrition pre-workout: https://bit.ly/3y5qxRI
1Up Nutrition L-Carnatine: https://bit.ly/3ogmo9b
Nutrafol Hair vitamins: https://bit.ly/3yeFEbu