I believe Colossians 1:19 reflects the different styles of the NLT Study Bible, the ESV Study Bible, and the NIV Study Bible quite well.
Forin him all the fullness of God was pleased to dwell…. (Colossians 1:19; ESV)
NIV Study Bible:
1:19 fullness. Part of the technical vocabulary of some Gnostic philosophies. In these systems it meant the sum of the supernatural forces controlling the fate of people. For Paul “fullness” meant the totality of God with all his powers and attributes (2:9).
ESV Study Bible:
1:19 For in him all the fullness of God was pleased to dwell. The “fullness” language here and throughout the letter is reminiscent of its use in the OT, where it was said that God “filled” the temple with his presence. For instance, the prophet Ezekiel exclaims, “I looked, and behold, the glory of the Lord filled the temple” (Ezek. 44:4). Jesus not only bears God’s glory, but all that God is also dwells in him. He possesses the wisdom, power, Spirit, and glory of God. To say that all this divine fullness dwells in Jesus is to say that he is fully God (see also Col. 2:9).
NLT Study Bible:
1:19 God in all his fullness emphasizes that God has chosen to reveal himself fully in Jesus Christ. Seeing Jesus and understanding him therefore means seeing and understanding God (see John 14:6-11). The false teachers seemed to be saying that Christians needed to look to other spiritual beings to find out more about God (see 1:16,20). But Christ is sufficient for all our knowledge of God (cp. 2:8-9).
The NLT Study Bible explains the fullness of God in Christ through the background of what the Gnostics (though Gnostics are not mentioned) were teaching the Christians in Colosse. The NLTSB gives a concise and clear explanation: Christ is all one need’s for knowledge and nothing more.
The ESV Study Bible explains the fullness of God by looking to the Old Testament. Personally, I had never considered this phrase relating to God filling the temple with his glory. Notice the ESV draws a different conclusion than the NLTSB: Jesus is fully God.
The NIV Study Bible zeroes in more on the word “fullness” arguing this word represents all of God’s powers and attributes. The NIVSB point seems to be that the Gnostics were using the word “fullness” and Paul borrows from their vocabulary to show that Christ is that fullness.
I will let you decide which explanation makes the most sense of Paul’s writing. Perhaps if we combine all three points from each study Bible and then we would have the “fullness” of Paul’s meaning here.