We can set a two factor in ProtonMail right?
Yes, you can use Authy or Google Authenticator. Just click on settings inside your account, click on "enable two factor authentication", and scan the QR code. It will also provide you with 16 "recovery codes" which can be used once each in the event you lose your phone or other 2FA device. Much like your mnemonic seed, you should write these down on paper and store them somewhere safe (not electronically).