All states other than California have adopted rules of professional conduct based upon the model rules of the ABA (or its predecessor, the model code). State adoptions sometimes include modifications from the model. California's rules are influenced by the model rules.
In addition to the ABA's model rules, the American Legal Institute (ALI) has a Restatement of the Law Governing Lawyers. To access the text of the Restatement, look at the "Restatements" tab on this guide.
The Iowa Rules of Professional Conduct are located in chapter 32 of the Iowa Court Rules. Sources include:
To find and understand rules from other states, try identifying resources by using a research guide or database that compiles state legal ethics sources.