A Virtual Private Server?
Maybe you could expand on the reasons why you need it so the community could help you in a way that maybe you don't know.
I doubt there are any free virtual private servers but you can always try free cloud hosting / free linux instances. For example,
for one year AWS offers free EC2 instance but you need to put your card for verification purposes.
Read here about VPS vs Cloud hosting
https://www.hostgator.com/blog/cloud-vs-vps-hosting/