Can hair weave/extension be relaxed?

Yeah, as long as it’s real hair.
If it’s synthetic hair like kanekolan, yaki etc.
THEEEEN forget it!

It depends on is it human or synthetic.

I have extensions. I don’t know if you can relax them but i do know that you can wash them, straighten them and curl but only if it is 100% human hair

You can do whatever U want with HUMAN HAIR extensions. For example, I personally use Goddess Remy (straight hair) and I chose to perm it (made the hair naturally curly). I did this because I wanted a certain curly hair look that the stores did not carry. After about 2 months, I decided that I wanted to go back to the straight look. Without purchasing new hair, I used another perm kit (making the hair bone straight again). It worked great, either way, whether going naturally curly or straight. I advise you to only do this with remy hair or virgin remy hair because with the cheaper brands, your end result may be all bad. But other than that, my end results were great. I got many compliments on the curly and straight hair look. Good luck…