The phrase "size into" refers to the process of gradually increasing or decreasing in size. Synonyms for this phrase include "gradually expand," "gradually enlarge," "gradually grow," "gradually develop," "gradually mature," "gradually increase," "gradually escalate," and "gradually intensify." These synonyms are often used in contexts such as describing the growth of a business or organization, the development of a relationship, or the progress of a project. Using these synonyms can add depth and variety to one's language, and can help to convey a sense of gradual change or progression over time.