I'm asking user on registration to upload an avatar images but, some images takes much time to be uploaded as it's very big or something, is there any way to reduce images size before send them with post request, i'm using nuxtjs.
Not really.
You could make a validation on the size and do not allow them if it's above a specific threshold.
Don't do image compression on client-side tho.
There are some ugly solutions here tho, like converting your image into a canvas and back, you will definitively get some sub-par image quality but it may be okay in your case?
This answer is still relevant too.