import re
newtxt="200 sample text with many lines\n hell01 \n hell02 \n hell03 \n hell04 \n hell05\n hell06\n hell07 \n hell08"
pattern = re.compile(r'^\d{3} [a-z].*((?:\r?\n.*){0,5})', re.M)
m = pattern.search(newtxt)
if m:
  print( m.group(1) )