After creating a chart (in Calc), selecting different elements of the chart shows different controls in the sidebar. 

Now, most selectable items offer the control of toggling the existence of a Legend for the chart. Which is ok. But - almost none of them have the toggle for labels for data series (neither all series or a single series). Specifically, selecting:

* A single datum's part of the chart (e.g. a pie chart slice)
* All data labels
* The plot area (e.g. the whole pie)
* A single data label

doesn't show that toggle. Only if you happen to select an entire data series, do you get it. And it is not trivial, in some chart types, to make that particular selection.

So, I suggest that toggles for data series labels, or perhaps toggles for elements of the chart, be accessible via the sidebar for more kinds of selected elements of a chart.