Try Apple Menu/About This Mac. Then click on System Report and, under Hardware, click on Power. Battery Information should be at the top, and under that will be Health Information. Condition is the main thing. If it says Normal, then your battery has ~100% capacity. I don't remember what it says when the battery has degraded (I changed the battery in my 2013 13" MBP a few months ago, but I don't use it much) but it will give you an idea. Here is Apple's explanation of cycle count:
Determine battery cycle count for Mac laptops - Apple Support