16? Still very possible if you ask me.
Age is just one factor by the way. Determination also plays a big role.
Instead of going for gm, try to go for higher rating. I'm almost 1300 rapid now. My next goal is 1400 when I reach 1300.
Gm title will come after you go up in rating.
So let's say I'm 16 years old right now. I learned chess when I was little, but I started playing serious and tried to get better starting the October of 2016. This is also the time I started playing on chess.com.
I learned that most masters started playing at a very early age, such as 8-10. So, is it still possible for me to become a master, when I started at 16, or am I too late?