I think you can use italics, a block quote, or just separating it in some way from the rest of the text. Some examples below.
Opening the letter, shadowdrake27 read the terrible news:
Dear Shadowdrake27,
Your COVID-19 test was positive, have fun dying.
-CDC
Opening the letter, shadowdrake27 saw four words that stuck out to him, COVID-19 test was positive.
Opening the letter, shadowdrake27 read the terrible news:
***
Dear Shadowdrake27,
Your COVID-19 test was positive, have fun dying.
-CDC
***
I hope that is helpful! I am not sure if you have a specific instance you are trying to use this for, but if you do, posting it will help someone give better advice! I think all three of the above methods can be used. Someone better at grammar could tell you if that is true or not.