'Full grown' in the Bible

Yet we do speak wisdom among those spiritually mature [believers who have teachable hearts and a greater understanding]; but [it is a higher] wisdom not [the wisdom] of this present age nor of the rulers and leaders of this age, who are passing away;

All of us who are mature [pursuing spiritual perfection] should have this attitude. And if in any respect you have a different attitude, that too God will make clear to you.

We proclaim Him, warning and instructing everyone in all wisdom [that is, with comprehensive insight into the word and purposes of God], so that we may present every person complete in Christ [mature, fully trained, and perfect in Him—the Anointed].

But solid food is for the [spiritually] mature, whose senses are trained by practice to distinguish between what is morally good and what is evil.

There is no fear in love [dread does not exist]. But perfect (complete, full-grown) love drives out fear, because fear involves [the expectation of divine] punishment, so the one who is afraid [of God’s judgment] is not perfected in love [has not grown into a sufficient understanding of God’s love].