.txt return specific lines or strings

[s_o_what]

I have a text file I would like to read and search. I need to find specific strings that could possibly be URLs. Once that is found I would like to store them in a list or set.

# Target file to search
target_file = 'randomtextfile.txt'

# Open the target file in Read mode
target_open = open(target_file, 'r')

# Print one line. The first line
print(target_open.readline())

Example .txt file:

This is a file:

Sample file that contains random urls. The goal of this
is to extract the urls and place them in a list or set
with python. Here is a random link ESPN.com

Links will have multiple extensions but for the most part
will be one or another.
python.org
mywebsite.net
firstname.wtf
creepy.onion

How to find a link in the middle of line youtube.com for example