[come] out (swinging|fighting)

to respond or react to something in a forceful manner

The exact origin of the phrase "come out swinging" is unclear, as it is a commonly used expression in English language and idiomatic phrases often evolve over time. However, it likely originated from the sport of boxing, where fighters enter the ring and begin a match by throwing punches forcefully and aggressively. The phrase captures the image of a boxer coming out of their corner swinging their fists, ready to engage in a fight with determination and intensity.

The underdog team came out fighting in the championship game, surprising everyone with their aggressive and relentless play.
The startup company entered the market by coming out swinging, aggressively targeting their competitors and offering innovative solutions.
In the heated political debate, the candidate came out swinging, attacking their opponents' policies and presenting their own vision with passion and conviction.
Despite the initial setbacks, the author's new book came out swinging with a provocative and thought-provoking opening chapter.
The employee faced criticism during the meeting but came out swinging, presenting a well-prepared argument to defend their ideas and contributions.