with open('old_file.txt', 'r') as f1, open('new_file.txt', 'w') as f2:
    lines = f1.readlines()
    lines.reverse()
    f2.write(lines)

with open('old_file.txt', 'r') as f1, open('new_file.txt', 'w') as f2:
    lines = f1.read()
    lines.reverse()
    f2.write(lines)

with open('old_file.txt', 'r') as f1, open('new_file.txt', 'w') as f2:
    lines = f1.readlines()
    for line in reversed(lines):
        f2.write(line)

with open('old_file.txt', 'r') as f1, open('new_file.txt', 'w') as f2:
    lines = f1.read()
    for line in reversed(lines):
        f2.write(line)