I attempt to answer that question in this article:

Naselli, Andrew David. “Harmony of the Gospels.” In The Gospel Coalition Bible Commentary, 2022.

Outline:

1. Presuppose That the Gospels Do Not Contradict Each Other

• Reason 1: The Gospels Are God-breathed Scripture
• Reason 2: The Gospels Are Historically Reliable

2. Understand Why the Gospels Have Apparent Contradictions

• Reason 1: The Gospels Paraphrase and Interpret Events and Sayings
• Reason 2: The Gospels Abbreviate and Omit Events and Sayings
• Reason 3: The Gospels Reorder Events and Sayings
• Reason 4: The Gospels Report Similar Events and Sayings

3. Compare the Gospel Accounts with Each Other, and Responsibly Discern How They Harmonize

4. Focus on Understanding Gospel Passages in Their Literary Context

Further Reading