Twitter sends email notifications with the subject in small letters raised above the base line:
How can we do this in our messages?
They insert Unicode superscripts in subject line. You can do, too: there are sub/superscript generators online, for example this one. Example:
da_667ᴺᵉᶜᵏᵇᵉᵃʳᵈ ᵗᵒᵒ ʰᵃᶦʳʸ ᵗᵒ ʰᶦᵈᵉ Tweeted:
In principle, one can type these directly but you'd have to know the Unicode code points and how to use them to enter characters on your device.
