I don't think the word has been used is a different sense, but the passage only teaches about the attitude of perseverance and humility among believers, since the goal of a Christian saint is to attain perfection. Maturity is not so suitable word for telios in many instances even though maturity is a metaphor for perfection. Cf. Matt 5:48
Matt 19:21
Rom 12:2
1Cor 2:6
1Cor 13:10
Eph 4:13
Phil 3:15
Col 1:28
Col 4:12
Heb 5:14
Heb 9:11
Jas 1:4
Jas 1:17
Jas 1:25
Jas 3:2
1John 4:18.
Eph 4:12-13 KJV
12For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: 13Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect (teleios) man, unto the measure of the stature of the fulness of Christ:
In Paul's Letter to the Philippians Edward D. Andrews, Thomas F. Marshall · 2022 writes,
If we look at 3:12, Paul informs his readers that he did not see himself as being perfect at the time of his penning this letter. He wrote, “Not that I
have already obtained it or am already perfect [teleios], but I press on ..."
“These two verses are not contradicting each other. Being one of the most
‘mature Christians of all time, Paul did not view himself as perfect, stating that
he had not reached the ultimate goal, knowing that he had to continue to
‘make advancements in his maturity in this imperfect age of humanity. So, we
all the more so need to make advancements toward complete maturity.
John Eadie commentary is very good,
The language used by the apostle -ὅσοι-intimates that all were not τέλειοι in the Philippian church; the idea of relative progress is therefore involved. Nor does it, as Wiesinger objects, in any way give countenance to self-esteem, for he neither names the τέλειοι, nor points out precisely in what their perfection consists. On the other hand, he classes himself among the τέλειοι, and yet he has declared of himself that he was yet not perfected. In fact, the perfect one was only in the way of being perfected; none knew his imperfection so much, or felt it so deeply, and therefore he strove with quenchless ardour to move fleetly onward to the end of the race, and obtain the crown. For one may be perfect in aim, and yet be far from realizing it. The perfection referred to was such a progress as vividly showed defect; such a stage in the race as revealed most painfully the distance lying still in front; such light which, as it grew, served also to enlarge the circle of darkness round about it. Chrysostom's notion is peculiar—“What means the word? (τέλειος). This-that we should forget those things which are behind. Therefore it belongs to him who is perfect, not to regard himself as perfect:”-
If we translate the second instance of perfect as mature, as what is seen from the New Versions, it loses the wordplay; however, it may give reason for the idea against perfection if that word has been avoided. The NET paraphrase version on Philippians 3:21 Therefore let those of us who are “perfect” interprets the statement as sarcasm to draw the anti-perfection lawless conclusions, quote opposite to the overall text. Such versions employ curious tactics of reading the minds of the authors, assuming any verse to be sarcasm and attack to his "opponents". NET notes states:
3:15 [23] tn Grk “those of us who are ‘perfect’ should think this,” or possibly “those of us who are mature should think this.”sn The adjective perfect comes from the same root as the verb perfected in v. 12; Paul may well be employing a wordplay to draw in his opponents. Thus, perfect would then be in quotation marks and Paul would then argue that no one – neither they nor he – is in fact perfect. The thrust of vv. 1–16 is that human credentials can produce nothing that is pleasing to God (vv. 1–8). Instead of relying on such, Paul urges his readers to trust God for their righteousness (v. 9) rather than their own efforts, and at the same time to press on for the prize that awaits them (vv. 12–14). He argues further that perfection is unattainable in this life (v. 15), yet the level of maturity that one has reached should not for this reason be abandoned (v. 16).
Even though maturity is a metaphor of perfection, the translator's and Bible editor's bias against obedience and striving for the goal can clearly be found. For this reason the reliable textual variant addition "have already been justified" η ηδη δεδικαιωμαι is conspicuously avoided in the Bibles versions.
To answer the question, of course, Paul was perfect, but he taught a humble attitude which never retires from the work, until the ultimate realization of the perfection and justification he hopes for, which is after the resurrection. He must maintain the perfection till the finish line. What he denied is not perfection in general, but the sense of achieving pinnacle and culmination of the mission.