Works of art that express a confident/bold tone might depict characters that are self-contained and self-assured. Beyond representation, art elements such as full value range from light to dark, bravura brushstrokes, hard edges, or thick outlines might contribute to a confident/bold feeling.
An artist might impart a confident/bold tone to a piece due to his or her own bravado, or the artist might choose to evoke this tone as a reflection of the character(s) or scene being portrayed. A confident/bold tone might also be adopted to suit a piece that will be shown in a setting that demands an expression of strength.
Featured: Christina of Denmark by Hans Holbein the Younger