“Go for It.” Can Simply Mean “Yes, Go Ahead”

“Go for it” often encourages someone to make an attempt: pursue it and give it your best. In everyday Australian conversation, however, it can also grant permission readily:

“Mind if I use this chair?”
“Go for it.”

Here, the speaker is not urging the other person to strive for a goal. It simply means “Yes, go ahead and use it.” “Please do it” would sound more like an instruction. The phrase is friendly and informal, suited to colleagues, friends and relaxed service encounters. In a formal exchange, “Certainly” or “Of course” may fit better. The same conversational use is understood in British and American English.

https://www.collinsdictionary.com/dictionary/english/go-for-it