Amplify: Amplifying is a related term that means increasing the intensity or strength of something. In the context of modifying an argument, amplifying involves making certain parts more forceful or prominent.
Strengthen: Strengthening refers to reinforcing or making something stronger. When applied to modifying an argument for emphasis, strengthening involves adding weight and power to specific elements within the argument.
Highlight: Highlighting is another related term that means drawing attention or focusing on something important. When used in relation to modifying an argument, highlighting entails emphasizing key points in order to make them stand out more prominently.