How to make seaborn.heatmap larger (normal size)?

Before using heatmap(), call matplotlib.pyplot.figure() with the figsize parameter to set the size of the figure. For example:

pyplot.figure(figsize=(10, 16))
sns.heatmap(...)

The two elements of the tuple passed to figsize are the desired width and height of the figure in inches. Then when you make the heatmap, it will stretch to fill the available space given that size. You may have to do a bit of experimentation to determine what size looks best.

import matplotlib.pyplot as plt

plt.figure(figsize=(12, 9))

sns.heatmap(df)