The “EnableSLIMAvatars” property section states “This property cannot be set through scripting” and then proceeds to contradict the statement by stating that it must be set through the command bar, or a plugin, both which involve scripting. Additionally, there is a UI chip stating “Not Scriptable”. The reality is that the property is completely inaccessible to developer facing Luau as attempting to access it in any way will cause EnableSLIMAvatars is not a valid member of Workspace "Workspace" error to be thrown.
Thanks for submitting this feedback. Our docs often use “can’t be accessed through scripting” (or some equivalent) to denote the inability to set/get the property through developer-facing Luau, but, as you mentioned, it’s not the most precise or comprehensive terminology.
I’ve submitted a change to make the language on this (and a couple other APIs) a bit more clear that they can’t be accessed by developer-facing Luau, and I also encourage you to flag any other API documentation you think might not be accurate.