First of all, you have to confirm whether the product has been patented abroad. If not, things will be relatively complicated. You need to find a special patent lawyer to prove that the relevant patents applied by this domestic company are well-known technologies. Then apply to the patent office for this domestic patent to be invalid.
If the product has applied for a patent abroad, it depends on the application time and scope of protection of the patent, and it is proved that the two are the same, or the domestic one is not novel, so things are relatively simple, and it can be invalidated only by applying for a domestic patent.