All 4 gospels are apologies.
Matthew defends Jesus to Jews as fulfillment of the OT and the Jewish Messiah.
Mark defends Jesus to Gentiles as the God-Man and suffering servant of Isa 53.
Luke defends Jesus as the Son of Man (Dan 7:13) and Davidic son.
John defends Jesus as the Son of God, co-equal and co-eternal with the Father.

From Matthew to Revelation, much of the NT is an apology. Examples: John 20:21; Luke 1:1-4; Acts 1:1-3; Rom 1:16-17; 1 Cor 2:1-5; 2 Cor 10:5; Phil 1:7,27; 2:9-11; Col 1:15-20; Hebrews; 1 John 1:1-3; 1 Pet 3:15-16; Jude 1:3

Galatians stands as an eloquent and vigorous apologetic for the essential NT truth that people are justified by faith in Jesus Christ—by nothing less and nothing more—and that they are sanctified not by legalistic works but by the obedience that comes from faith in God’s work for them, in them and through them by the grace and power of Christ and the Holy Spirit. It was the rediscovery of the basic message of Galatians and Romans that brought about the Protestant Reformation.

The book of Acts provides specific examples of people doing apologetics, speaking to people who are skeptical. The earliest and clearest examples are the seven Kerygmatic (proclamation) sermons. Looking at Acts 4:8-12, Peter is seeking to convince people who do not believe. The audience is Jewish. The central claim is that Jesus the promised Messiah, raised from the dead. Contrast that with Paul’s speech in Acts 17:22-31 to the pagan Athenians. Paul starts with God as Creator and ends with Jesus as the final Judge and a call for repentance. Apologetics is always specific for the culture, but the gospel remains the same and is always the goal.

The evidence provided in these apologetic speeches changes based on the audience but the central claim of the death and resurrection of Jesus never changes; it is central in every case. The other speeches in Acts are 2:14-36; 3:12-26; 5:27-32; 10:34-43; 13:16-41; 17:22-31 – a total of seven different speeches. In these speeches, the evidence changes based on the audience, but the death and resurrection of Jesus is central to every speech.

The gospel is both the goal and the lens through which the apologetics happens. The ultimate goal of apologetics must always be the gospel.

And he (Jesus) answered, “You shall love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind” (Luke 10:27 ESV).