I wanted to ask if I should double major in anthropology due to the lack of exposure? I feel like I should've double majored in anthropology initially since there's more courses offered related to ancient history than the history department currently offers.

I think this heavily depends on your department (and on where you'll eventually apply for graduate programs, but I don't expect you to have any firm ideas on that yet). If you have space in your course load to take those anthropology courses without taking on an additional major, that's certainly an option; if your history department is flexible, they may even allow you to count some of those courses for your history major upon petition. (You should reach out to the department's undergraduate studies coordinator/analogous position to ask about this possibility.)

Are you planning on writing some sort of final thesis? This, too, would be a good place to draw on the anthropology department's resources without formally double-majoring—you can ask the relevant faculty member/s to informally advise you on your project, and hopefully forge the sorts of connections you'd need for them to write you a letter of recommendation. In the end, these connections are far more valuable than a double-major would be (since, again, you could likely do all the coursework without dealing with any bureaucratic red tape).

Edited to add: my experience has been that admissions committees don't really care about double-majoring, and doing so might force you to water down your coursework with classes you're not interested in (anthropological methodology, fieldwork, etc.). If you can avoid this by talking to the relevant faculty and staff—both within the history department and in the anthropology department as well—you should be able to get all of the benefits of double-majoring with none of the drawbacks. Just make sure you mention it in your eventual statement of purpose!

You might want to choose between Mesoamerica and Classics/Mediterranean stuff, and then also choose within the Mesoamerican groups. For Mesoamerica, the most famous precontact scholars in the field today do not study the Mayas or the Aztecs from an ancient or classics perspective. They generally come from archaeology, anthropology, and art history, who mostly or exclusively focus on Mesoamerica (although they may have taken courses on other parts of the world during undergrad and grad school, or do some comparative work). Mayanists rarely study Central Mexico for example because the languages and scripts were different (again, exceptions because there was lots of contact between these them, which people do study). Scholars on the Aztecs don't do a ton of Maya epigraphy. I suppose there are some comparative religion scholars as well. Actually, very few historians study the precontact Maya. As far as I know, all of the famous epigraphers among Mayanists come from archaeology. The Aztecs on the other hand were a relatively new society, arising in the fourteenth and fifteenth centuries, so there are historians who study the precontact Aztecs (e.g. Camilla Townsend's recent great book Fifth Sun), even though there are also a lot of archaeologists. You might want to ask over in /r/askanthropology for advice. Or maybe there is an archaeology subreddit.

If you want to study Mesoamerica, you might consider beginning to learn a Mayan language or Nahuatl. These modern languages will help you read the precontact texts that you seem to be interested in. You may be able to find a summer program through your study abroad office. Or maybe your university offers courses. These programs might also be a way to go to Central Mexico, Yucatan, or Guatemala and learn about indigenous people and cultures.

I would also encourage you to just keep taking classes and see what is interesting for you. If your schedule allows, try those anthropology courses you mentioned, even if you don't end up majoring in it. Maybe you can get a minor out of it. You have a long way to go before you would even apply for graduate school. Who knows what other twists and turns await you, which might take you in a different direction...or out of academia all together. Don't fear exploring a little. Are you sure you want to do super ancient stuff? Take some other classes on early modern or modern history. Begin doing primary source research whenever you can. What areas of research pull you? Dial in which geographic area you want to focus on. Maybe do a study abroad semester to that place, pandemic permitting? Also consider what other jobs might make you happy. Most people who dream about going into academia as undergrads, end up doing something else. That's ok! You can start down the road thinking about academia, but then end up heading in a totally different direction because some great opportunities came along along the way. But by the time you graduate and are still thinking grad school, you want to have built connections with people to write letters of recommendation for you and also have done research that you can turn in as a writing sample. So in the short term, keep exploring and find specifically what you like. In the medium term, do some primary source research. Once you've done that, reassess if you still want to go to grad school.