It is entirely possible to change the shape of mean markers on box plots, and the fact that this question even needs to be asked tells us something important about the tools we have been using. For too long, spreadsheet software has hidden simple customization options behind layers of menus, obscure formatting panes, and workarounds that require more patience than skill. The user who posted this question is not asking for something exotic. They want to control a single visual element, the marker that represents the average, and they know it can be done on scatter plots. The assumption that box plots might be different reveals a deeper frustration: the feeling that some features are locked away for no good reason.
What this means in practical terms is that many users are spending time searching for basic formatting controls when they should be focusing on the data itself. The mean marker is a standard component of any box plot worth building. It tells you where the center of your distribution sits, and its shape, circle, diamond, square, triangle, can make a chart instantly more readable, especially when you are comparing multiple groups. Changing that shape should be as straightforward as changing a font color. The fact that it is not is a sign that traditional spreadsheets were designed around what the software could do, not around what the user needed to accomplish.
We believe this is exactly the kind of friction that an AI-native approach to spreadsheets eliminates. When the tool understands your intent, it does not make you hunt for a checkbox buried three menus deep. It anticipates what you want and presents the option plainly. The user who asks "is it even possible" is not asking about technical feasibility. They are asking whether the tool respects their time. That is a fair question, and the honest answer from legacy software is often "yes, but you will need to look it up." A smarter tool answers with "here is how, and here are three other ways to improve the chart while you are at it."
The solution is not to memorize another workaround. It is to demand a spreadsheet that treats customization as a natural part of the workflow, not a hidden Easter egg. If you find yourself asking whether a basic formatting change is possible, take that as a signal that the tool is working against you, not for you. The next time you build a box plot, ask yourself what else you might be missing. Then find a tool that does not make you wonder.