Question

How to set a max value on the Y-axis of the bar chart (scale)?

Answer

The max value on the scale of the bar chart can be changed via the customization menu
Please navigate to customize editor:

From here navigate to Chart settings►scales►1►softMaximum
set the value of softMaximum to needed

Please note: if your bar chart has a histogram bar with more than that value, the new value of softMaximum will not be applied
Example:

After changing it to the lower value: