CODE EXAMPLE FOR PYTHON

seaborn colorbar labelsize

import matplotlib.pyplot as plt
import numpy as np; np.random.seed(0)
import seaborn as sns
data = np.random.rand(10, 12)*100
ax = sns.heatmap(data, cbar_kws={'label': 'Accuracy %'})
ax.figure.axes[-1].yaxis.label.set_size(20)

plt.show()