assuming you're asking about CCC charts, scrolling happens if the chart grows beyond the initially given size, either horizontally or vertically, and, you've activated scrolling through CSS's overflow attribute.
Certain charts can grow beyond their initially given size. When multi-charts are used, this happens for any chart (that supports multi-charts). Otherwise, growing happens if certain options are used which impose a minimum size. For example, baseAxisBandSizeMin imposes a minimum on the size of categorical bands of Bar charts, Heat-grid, and Line/Area/Dot chart (when used with a categorical "category" visual role). The Heat-grid supports the same behavior for the "series" visual role and the orthoAxisBandSizeMin option.
Hope this helps.