text decoration
Refers to visual enhancements applied to text, such as bold, italic, underline, color, or font effects. Common in computing and design contexts.
With this software, you can easily apply text decoration.
Overusing text decoration makes it hard to read.
書式 refers to overall formatting (layout, margins, etc.), while 文字装飾 specifically targets visual effects on characters.
Compound of 文字 (character) and 装飾 (decoration).