The feature is only available on mobile Metamask apps. It can't be done on Metamask browser extension on other devices. Anyway, right now the mobile sync feature is disabled, so you can't do it either way.
The mobile sync is disabled since a lot of people get deceived by the scammer that make use of that mobile sync.
Yes I know but at least you can synchronized your metamask account on your mobile since the extension can provide qr code to scan for your mobile app metamask rather than manually import your seed phrase. That's also the problem if you are not careful on what you scan as it might be the scammers trap. It's no worry if you scan it from your metamask extension.
Both method are safe for me, what is the root cause of this type of hack and any type of hack is the user itself, a user that is careless enough to lose this way can as well lose in other way. We should all the time focus on security and making out online vicinities safe from hackers. We should not trust anyone, we should make sure we do not use our device used for operating our wallets to always go online which is where the attacks are from.