The phrase "leaps into breach" is commonly used to describe a situation where someone takes a bold and courageous step to fill an important gap or address a critical issue. However, there are several other synonyms one can use to convey the same message. For example, one can say "dives into the fray," "charges into battle," "plunges into action," "throws themselves into the fire," or "takes the plunge." In all of these cases, the idea is to convey a sense of bravery and determination, as well as a willingness to take risks in order to achieve a certain goal. By using a variety of synonyms, a writer can add depth and nuance to their descriptions of individuals who boldly go where others fear to tread.