Can I apply for a visitor visa after applying for immigration to the United States?

Visiting relatives is a B 1/B2 visa, and even friends can do it (regardless of the success rate).

If you immigrate, it is best for parents, husbands and children to help you apply, so the success rate will be higher. Your uncle can do it, but it's far-fetched. For example, your parents are in China, your uncle is in the United States, and then you and your uncle apply for immigration together, so people have to convince others convincingly why you can "abandon" your parents and go to the United States to go to your uncle.