How to replace the rear passenger side freeze plug?

This depends on which one you are talking about, you may need to lift the engine on one side and use a long extension to knock the freeze plug inward and then use large pair of pliers to remove the old soft plug, this tool is used to reinstall the new freeze plug.

https://amzn.to/3J3iNaH

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.

The rear passenger side.

If you can upload picture of the job I can help walk you through it. There is no straightforward way to do freeze plugs it is by a per case operation.