When people spoke in a formal way in the past, was it actually formal? Or did it feel casual to them? written by u/macnfleas and u/yodatsracist may interest you

Additionally, Why did people write much more eloquently 150 years ago? by a now deleted user talks about both speech and writing. (The thread also features excellent replies by u/Impersonating-Cactus and u/TheSoundOfTastyYum, but their answers are less relevant to your question