How to clip out lat-long for individual participants to a corresponding area map in R?

This is definitely possible using the sf package. In order for us to help you, could include some exmaple data as a minimal REPR oducible EX ample (reprex)? A reprex makes it much easier for others to understand your issue and figure out how to help. See here for more info on making a reprex:

Additionally, I've written up an example of doing this point in polygon operation on my blog. See here for a walk-through of the process: