I use yaytext.com/bold-italic (other similar siteds) which converts text (I normally cut and paste into it) into 𝐁𝐨𝐥𝐝 (𝐬𝐞𝐫𝐢𝐟), 𝗕𝗼𝗹𝗱 (𝘀𝗮𝗻𝘀), 𝐼𝑡𝑎𝑙𝑖𝑐 (𝑠𝑒𝑟𝑖𝑓), Italic (sans), 𝑩𝒐𝒍𝒅 / 𝒊𝒕𝒂𝒍𝒊𝒄 (𝒔𝒆𝒓𝒊𝒇) and 𝘽𝙤𝙡𝙙 / 𝙞𝙩𝙖𝙡𝙞𝙘 (𝙨𝙖𝙣𝙨).

𝑾𝑨𝑹𝑵𝑰𝑵𝑮 once you have converted text to one of the fonts, you can't change it back (I haven't found a program that does)