Years ago most viruses were written for Windows but those days are long gone. Google “antivirus for Apple” and pick one. I really like BitDefender.

Much of the malware of yesteryear got in through the various browsers of the time. Choose your browser wisely.

Been using their products for years and very satisfied with their services.

Here are free scanners (all with premium features for $$ )
https://www.safetydetectives.com/blog/best-really-free-antivirus-for-mac/

No advice on ios.

TBH, the most common freakish behavior I've seen is the "your device is infected ... please call and send money" one where a script gets your browser in a tight loop, looking like all hell, but that's just a trick to panic you. Kill the browser and delete the page if it pops back, before it goes off again.

Merci!

Mme. D.