My first reaction is, “Well that depends!” To be specific, it depends on the scenario.
Scenario 1 is editing or writing a book or long document to be read by experts and aficionados but also by the uninitiated and managers who have only a general knowledge of the subject.
Organization is our secret weapon here. The text can begin with a general introduction that all can understand to establish the subject at hand, the purpose, and the tone. It could be about how to start a business at home and keep proper records, and it could have either a serious accounting tone or a humorous how-to-make-your-taxes-easier-to-file tone. (The manager in this case might be the publisher who will decide whether to publish the book.)
In this introduction or immediately after, sections can be listed and even linked to so users can find what they need. Each section can begin with a general explanation, but this can be followed with details and can use vocabulary necessary to be specific. The supervisor and the uninitiated may not be familiar with the specialized vocabulary or follow all the details, but they may be skimming these parts, anyway. A concluding section can be similar to the general introduction in terms of vocabulary and details. If it’s a long book, each chapter can be organized as seen above.
Scenario 2 consists of giving a semi-interactive talk or lecture to a live audience (or one online with chat allowed) that includes very literate people and experts on one end of the spectrum and, on the other end, novices and people with limited vocabularies.
I became good at this as a college professor. My own professors at the University of Wisconsin-Madison in the 60s were like stars of greater or lesser repute. Professors Whitley, Kroeber, and Mosse were famous on campus and beyond, and students who were not even enrolled in their classes came to listen to them. We increased our vocabularies by listening to them. They, and nearly all of our professors, stood in front, even on the stage in many cases, and held our attention by lecturing.
When I became a college instructor at a small college, however, it took very little time for me to realize, as I tried to make eye-contact with my students, that some were with me, and some clearly were not. Lecturing as my professors had done was not working. So I began saying things in several different ways and asking questions. How is the Golden Chain of Being they believed in during the early Renaissance different from the later idea that governments rule by consent of the governed? Why is it a pun when Hamlet says to his uncle, who married his mother, 'Not so, my lord; I am too much in the sun'? (Hint: son/sun.)
I tried to get discussions going. Although our texts used fairly high-level vocabularies, I concentrated on breaking the subjects down so they would be understood by the majority of my students. I couldn’t actually teach if I wasn’t making myself understood.
Scenario 3 is giving a sermon (or maybe a TED Talk?) to a congregation or group whose members have various levels of expertise and verbal proficiency when interaction is not allowed or not customary.
This is the most challenging scenario to be discussed here. The study of audience and purpose can’t be dispensed with, and attention-getting devices must be considered as well. What is the main objective of the talk? What details and examples are crucial for the audience to understand? How can repetition, touching or memorable examples, and a structure that culminates in the main idea be used to facilitate understanding? Are there certain words or phrases that are essential to understanding the main idea and supporting points? In that case, how can these words be defined and redefined so that they become part of everyone’s tool box?
To my mind, Arthur Brooks’s TED Talk on work and happiness https://www.youtube.com/watch?v=sDH4mzsQP0w&t=74s is an excellent example of a lecture that can be appreciated by nearly everyone, although some may miss his man on the motorcycle on a dirt road metaphor.
Come to think of it, perhaps Alvin Whitley, Karl Kroeber, and George L. Mosse knew how to include us all when they lectured, whether they did so instinctively or as a result of years of practice.