I keep getting messages from apple.com that my phone is infected and I need to download an app to cleans it is this a scam

Are you seeing something as shown in the pic below? This is neither a hack nor a virus. It is spam and you can get rid of it. Read below...

Then probably you have accepted an offer or subscribed for a spam Calendar accidentally. Watch the GIF below to know how to unsubscribe from these alerts. Look for an unknown Calendar on the device under subscribed calendars.

The messages are NOT coming from Apple. These are scams that are trying to trick you into buying useless software that will do nothing to help your iPhone.

Delete these messages.

Keep the iPhone updated to the latest iOS always and never Jailbreak. That's it.

iOS / iPadOS devices cannot be infected with Virus / Malware / Spyware if it is updated to the latest iOS/iPadOS unless you have intentionally downloaded spurious software or unauthorized apps directly from the internet and installed them on your device or/and have Jailbroken.