import numpy as np
import matplotlib.pyplot as plt
import matplotlib.colorbar as mcolorbar

fig, axs = plt.subplots(ncols=3, sharey=True)
for ax, aspect in zip(axs, (20, 40, None)):
    cs = ax.contourf(np.arange(24).reshape((4, 6)), levels=[2, 4, 8, 16], extend="both")
    cax, kw = mcolorbar.make_axes(ax)
    if aspect is not None:
        cax.set_aspect(aspect, anchor=(0.8, 0.5), adjustable='box')
        ax.set_title(f"Cbar aspect is {aspect}")
    else:
        ax.set_title("No cbar aspect")
    cbar = fig.colorbar(cs, cax=cax)
    print(cax.get_aspect(), cax.get_adjustable())
fig.savefig("colorbar_aspect.png")