I will use Oxandrolone. What is the risk that I stop growing?

 I am 16 years old with 1.77 tall (5'10)
I think I'll naturally stop at 1.80 or 1.82 (5'11 or 6ft)
Could I expand my growth to at least 6'1 or 6'2?

you cannot buy anavar(Oxandrolone) without the prescription so you will be buying an underground product from some dodgy source. That means you will be actually getting Winstrol (Stanozolol) and it will very quickly fuse your bones. Just the reality of BB.

Edit
also youre too old for anavar and your tanner stage is too late. Anavar if usually given to kids with idiopathic short stature with delayed puberty and those kids are around 13-14.  Without any pubes which most likely is not the case with you.

https://www.ncbi.nlm.nih.gov/books/NBK470280/

read it.

the steroid hormones accelerate the closing of the osseous epiphyses causing you to reach the bone age before the correct time if this happens you stop growing before the correct time, do not do that.
play sports, get plenty of time every day until age 18, as well (look for flexible diet) to optimize macro nutrients,
sleep well, because your growth and muscle recovery will occur in the sleep period. doing these things you can magnify maybe 1 inch.
this is not a rule,
but if your dad is 5'11 at least 5'10 and your mom is not so short, you probably get in the 6 feet ... maybe up to 6'1
see the calculation that gives a height average for the children in centimeters:
height of the father + height of the mother / 2 + 13cm
example
180 + 165/2 + 13 =
345/2 + 13 =
172.5 + 13 = 185.5 (6'1)

ridiculous posts nowadays, I cant stop laugh