Я думаю, это то, что вы ищете
from lxml import etree
# opening the source file
with open('test.xml','r') as f:
# reading the number
data=f.read()
parser = etree.XMLParser(recover=True)
# fromstring() parses XML from a string directly into an Element
x = etree.fromstring(data, parser=parser)
# taking the content retrieved
y = etree.tostring(x, pretty_print=True).decode("utf-8")
# writing the content on the output file
with open('test1.xml','w') as f:
f.write(y)
Хорошего дня