Generally, typographic techniques -- using bold, or italics, or both, or changing fonts -- are the least effective methods because they are very subjective.
The stronger techniques are to either describe how the speaker is talking, or show other people reacting to their tone and words.
You can use similes or metaphors.
"You made a mess," said John, sounding like a teacher who was more disappointed than angry.
You can just be declarative.
"You made a mess," said John, sternly.
Or you could exchange 'said' with an appropriate tag -- 'castigated,' 'criticized' maybe. Using said/asked is the preferred pattern, but other tags are fine. It's about the ratio they are used. I counted up said v. non-said tags in a Stephen King novel and he used non-said tags between 5-10% of the time. It's efficient.
The strongest technique is for the dialogue to carry the entire burden of conveying the tone.
"Your answers on the final exam are entirely unacceptable for me to consider giving even a passing grade in this course."
In this method, it's helpful if you've already established speech patterns or word use that link the speaker's attitude with the words. People often fall into subconscious patterns that communicate their inner emotional state to others, so it's not a silly writer's trick.