Does my mac have a virus?

The only malware that you can install, "Adware," isn't technically classified as malware, but it essentially is.

Etrecheck or MalwareBytes Anti-Malware for Mac should be able to find and remove Adware.

MBAM started its life as a nice tool designed to just remove Adware, but it has become too overbearing for me to heartily recommend it anymore. However, it may be able to detect things that Etrecheck cannot.

Also, what you think may be malware might just be incompatible software you have installed.

If your Mac has a virus, it would be the first! Mac don't get viruses. As far as other malware like adware you can run Malwarebytes. It's is about the most proven anti-malware software for Mac. It’s the only one recommended by Apple tech support folks.

https://www.malwarebytes.com/mac/

But what makes you think you have malware?

Run Malwarebytes or Etrecheck as Barney suggests.