Yea semrush and spyfu will tell you what keywords they are ranking for. That should give you a little hint on what they try to rank for or give you some
ideas for your keyword research. Taking it further, they may target some keywords they don't rank for yet. So go look around at there site, see what H1 tags they use, what keywords they bold or italic etc... That would give you a pretty good picture on what they try to do. This especially is useful because semrush would give you only what they rank for in the top20, so semrush etc...would not help you see the big picture or what they are up to. They may have found some nice keywords they want to rank for(that you should to) but because they just starting promoting that keywords they are not yet in the 20's so semrush wouldn't show you.