Can I customize the space between the chart label and legend?

Yes. You’ll want to look at the Chart.js docs to see how you might do that and then apply your changes via theme or a filter hook.

https://github.com/methnen/m-chart/wiki/Themes

https://github.com/methnen/m-chart/wiki/Action-and-filter-hooks#m_chart_chart_args

Oh, thanks! @methnen

It seems much more complex than I thought, I save it for the later reading.