A list of publicly available online resources for those wanting to learn causal inference.
Instrumental variables, difference-in-differences, synthetic controls: are these the statistical techniques you want to learn how to use? If so, read up online. Causal Inference: The Mixtape by Scott Cunningham and The Effect by Nick Huntington-Klein are good starting points. Both books not only contain good discussions (i.e., a chapter for each causal inference method) but also provide datasets and code in Stata, R, and Python.