iPhone X and XS battery can not be universal, tell you can be universal are changed battery. The wiring interface of the two battery buttons is not the same, Apple does not have a battery model that can be universal, do not think that it can be universal because the third-party battery does the same capacity, barely universal may have security risks, it is not recommended to try.
The battery products of iPhone X and xs are not universal, they are the battery products used by two different electronic devices of Apple, no matter the model of the product and the size of the battery capacity are different. Do not buy the two kinds of batteries incorrectly, otherwise the installation will not be able to affect your use. I hope my answer can help you.
No, Apple each battery accessory has a model that belongs to the machine