I am looking for CS PhD programs in the US. I am currently an undergraduate and have conducted summer research in Theoretical Computer Science/Coding Theory. However, this is not something I wanna specialize in grad school. I want to study something more like AI/Data Science. Is it going to hurt me that I do not have research experience in AI? What is the case for the top 10-20 CS PhD programs? I am worried because I feel like it is going to be problematic when writing my SOP -- I want to work/study something I do not have research experience in.
This isn't a problem for US doctoral study. The doctoral education process is long, and it normally involves coursework that you can use to refocus. Relatively few US doctoral applicants have much if any serious research background as the US undergraduate education system doesn't provide enough specialization or time to do it. And, switching fields is fairly common here.
Get good letters from people who can attest to your potential for success.
You will have plenty of time in a six (more or less) year program to get the experience.
See the answer for the US to this question for more: How does the admissions process work for Ph.D. programs in Country X?