With all below code snippets you can create a 3 * 3 matrix with python:

First method: Appending columns inside of loops for each row

rows = 3
cols = 3

lst = []
matrix = []
for i in range(rows):
    for j in range(cols):
        lst.append(0)
    matrix.append(lst)
    lst.clear()

print(matrix)
# the output will be: [[0, 0, 0], [0, 0, 0], [0, 0, 0]]

matrix[1][1] = 1
print(matrix)
# the output will be: [[0, 0, 0], [0, 1, 0], [0, 0, 0]]

Second method: 1 list comprehension outside and 1 concatenation operation inside

rows = 3
cols = 3
 
matrix = [[0] * cols for _ in range(rows)]

print(matrix)
# the output will be: [[0, 0, 0], [0, 0, 0], [0, 0, 0]]

matrix[1][1] = 1
print(matrix)
# the output will be: [[0, 0, 0], [0, 1, 0], [0, 0, 0]]

Third method: 1 list comprehension inside and 1 concatenation operation outside

rows = 3
cols = 3
 
matrix = [[0 for _ in range(cols)]] * rows

print(matrix)
# the output will be: [[0, 0, 0], [0, 0, 0], [0, 0, 0]]

matrix[1][1] = 1
print(matrix)
# the output will be: [[0, 0, 0], [0, 1, 0], [0, 0, 0]]

Fourth method: Using numpy package

import numpy as np
 
rows = 3
cols = 3
size = rows*cols
 
matrix = np.array([0]*size).reshape(rows,cols)

print(matrix)
# the output will be: [[0, 0, 0], [0, 0, 0], [0, 0, 0]]

matrix[1][1] = 1
print(matrix)
# the output will be: [[0, 0, 0], [0, 1, 0], [0, 0, 0]]