Welcome!
It would be most helpful if you posted both the R code and the error messages for installing readxl. Is this the only package that you are unable to install?
BTW, you are confusing R and RStudio. RStudio is where you write the code and R is where it runs. The latest version of R is 4.1.2. You have the most recent version of RStudio (2021.09.2+382).
Also, the first releases of a new macOS tend to have more bugs. Version 12.2.1 has been released with bug and security fixes. This is just general advice, not related to the package installation problem.