import matplotlib.pyplot as plt

plt.figure(figsize=(14,7)) 
plt.bar(x,y) 

# if you have plotted you graph directly using dataframe like this ↓
data.plot(kind='bar')

# then use this
plt.rcParams["figure.figsize"] = (14,7)

    plt.figure(figsize=(20,8))

plt.figure(figsize=(14,7))

import matplotlib.pyplot as plt
plt.rcParams["figure.figsize"] = (20,3)

from matplotlib.pyplot import figure
figure(num=None, figsize=(8, 6), dpi=80, facecolor='w', edgecolor='k')