Threshold to set colour for different scale range in Heatmap

As of R2019b, There is no in-built function to set the colour of different scaled range in heatmap. Perhaps, this function can faciliate you

How to use this function?
The function name is generatecolormapthreshold, first argument is the threshold and second argument is the colour

color= generatecolormapthreshold([1 10 25 30],[0 0.5 1; 0 1 0;1 0 0]);
h = heatmap(fluS,'DayName','noofweek','ColorVariable','Max_Data','Colormap',color,'ColorLimits',[1 30]);
h.FontSize=10;
h.Title='Heatmap';

means that range 1-25 is the colour for [0 1 1], 25-30 is the colour [1 0 0].