There are many resources you can access for consumer research and demographics, but some of these offer information beyond the scope of your project. Here are some tips for finding information about your company's customers:
For example: "taco bell" customer demographics
This search brings up business and industry magazine articles, such as this one from Business Insider:
You might also find some free "snapshot" information such as this one from Numerator (note that most of their company information is subscription-based).
Another example from Statista (again, most of their reports are subscription-based).