My iPhone 7plus is infested with virus, is it ok to update the software?

hopefully you didn't follow those instructions.. it's a scam or phishing thing. You did not have a virus.

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

shouldn't be any reason you can't update your software

All such messages are scams. Simply close the offending page, and avoid sites that are involved in such bogus advertising tactics.

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Unless you jailbroke your phone, you don't have a virus. What makes you think you do?

It's just a phishing attempt, everyone gets these. You are not infected.

Your phone did not have a virus. Any notice saying it does is a SCAM. If you followed the directions in that SCAM you have compromised your identity, which can now be controlled by the criminal that sent the SCAM notice to you. If you installed an app on your phone delete it IMMEDIATELY; the app itself might be used to hack your phone.

If you describe the notice and how you responded to it it may be possible to recover, but the best thing to do is to contact Apple’s Account Security Team—>Contact Apple for help with Apple ID account security - Apple Support

Kurtosis12 wrote:

It's just a phishing attempt, everyone gets these. You are not infected.

Unless the OP responded to the phishing message and gave away personal information, or installed an app, or connected to a VPN.

NO YOU DID NOT GET A VIRUS FROM A LINE CHAT POST!!!!!!

Read the other messages in response to your initial post.