How many times can I get a replacement for my iPhone?

Hi everyone I bought iphone 6s just a few days ago it was overheating so I returned it for a replacement I got replacement after they saw it overheat and after I got back the one I got is overheating too I'm kinda not too sure how many times I can get a replacement what you all think how many times can I get replacement before they say no more replacements if it's has problems

Btw the iPhone overheat after normal use our 10min youtube and I compared it with another iphone 6s that my friends have mine overheats and there's don't after 10 min youtube

As long as you're under warranty and the damage was due to some manufacturer defect, you'll be able to replace it.

Sound like they may have got a faulty batch or just extremely bad luck for you.
If you can, get your money back and purchase a 6s from another establishment.