$ pip install tkinter --user
ERROR: Could not find a version that satisfies the requirement tkinter (from versions: none)
ERROR: No matching distribution found for tkinter
$ python
Python 3.8.7 (default, Dec 22 2020, 00:00:00)
[GCC 10.2.1 20201125 (Red Hat 10.2.1-9)] on linux
>>> import tkinter
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'tkinter'
$ python -m tkinter
/usr/bin/python: No module named tkinter