"At a high peak" refers to being at the highest point or level of something. There are many synonyms that can be used to describe this state of being, such as "at its pinnacle", "at its zenith", "at the height of", "at its maximum", "at the summit", "at its apogee", "at the topmost", "at the acme" and "at its climax". All of these words and phrases convey a sense of being at the very top or peak of something, whether it is a physical or metaphorical height, accomplishment or achievement. Using these synonyms can help elevate the language and convey a more precise meaning.