too big for one's britches

Adjective

idiomatic not-comparable

(idiomatic) Disturbingly confident, unacceptably cocky. / Used other than figuratively or idiomatically: Too large to fit into one's pants.

Japanese Meaning

（比喩的表現として）異常に自信に満ち、行き過ぎたほど生意気、自己過信している様子。 / （直喩的意味）文字通り、ズボン（パンツ）に入らないほど大きいこと。

Being too big for one's britches, she dismissed everyone's concerns and made decisions without consulting the team.

図に乗って、彼女は皆の懸念を無視し、チームに相談せずに決定を下した。

Sense（1）

(idiomatic) Disturbingly confident, unacceptably cocky.

Sense（2）

Used other than figuratively or idiomatically: Too large to fit into one's pants.