convert_datetime("21.01.2022", "%Y-%m-%d", "%d.%m.%Y")

  
>>> import re
>>> 
>>> text = """convert_datetime("21.01.2022", "%Y-%m-%d", "%d.%m.%Y")"""
>>> 
>>> pat = r'\("(\d{2}\.\d{2}\.\d{4})"'
>>> match = re.search(pat, text)
>>> if match is not None:
...     out = match.group(1)
... 
>>> print(out)
21.01.2022
>>> 
>>> out = re.findall(pat, text)[0]
>>> print(out)
21.01.2022
>>>