On the effect of photography shooting pure white background

You must aim the camera at the white background to measure light before taking pictures, and then set the white balance to be customized, that is, set it to take pictures after you measure light.

So you can shoot it later.

Also, if you want to shoot white, you should appropriately increase some exposure compensation, because the camera measures light according to the gray scale of 18%, and the white object is gray by default, so how to shoot white?