Is there a tool that would make a point in the middle - or ‘centroid’ - of those sites in ArcGIS Pro?
"those sites" ?
Feature To Point—Data Management toolbox | Documentation if you just want to use a tool, otherwise, there are other methods depending on your familiarity with GIS
You could also calculate a feature that encloses the sites (Minimum Bounding Geometry) and then get the centroid of that feature:
Minimum Bounding Geometry—Data Management toolbox | Documentation
or you could calculate the Mean Center of the sites:
Hey @LauraLenhart, Dan and Bob have both provided some great tools to use, I'll add one more though that might be handy and that is the "Median Center" tool: https://pro.arcgis.com/en/pro-app/tool-reference/spatial-statistics/h-how-median-center-spatial-stat... which is robust to outliers within our data, and would mimimise the impact a outlier in our data has on our central feature,
All food for thought,
Cheers