This feature is actually not too echoed WhatsApp . Even so, you can already use the feature.
The way is also quite easy, but keep in mind that the font can be changed only one type, namely "FixedSys".
According ti the Mirror, Wednesday (20/07/2016), to change the font to FixedSys very practical. You do this simply by adding one type of character before and after the sentence you want to send.
All you have to do is add to the character ' three times before and after the sentence. For example, if you want to change the font the phrase 'how are you?' Then you just need to give characters such as '''how are you?'''. Voila! Message sent will be changed to the new font.
Especially for iPhone users, you certainly will not find `character on the keyboard. Therefore, if you want to change the font then you'll need to download any other keyboard in the AppStore.