The Great White Throne Judgment will not take place in heaven or on Earth, but somewhere between them in the spirit realm/dimension, after the earth and heaven have fled away at the appearance of the throne’s occupant. This cosmic location ensures that no one can enter God’s presence in heaven, nor remain on the fleeing earth.

The Bible describes that in this place, all the unsaved dead stand before the great white throne and are judged by God according to their works.

Below per GotQuestions.com

The great white throne judgment is described in Revelation 20:11-15 and is the final judgment prior to the lost being cast into the lake of fire. We know from Revelation 20:7-15 that this judgment will take place after the millennium and after Satan is thrown into the lake of fire where the beast and the false prophet are (Revelation 19:19-20; 20:7-10). The books that are opened (Revelation 20:12) contain records of everyone’s deeds, whether they are good or evil, because God knows everything that has ever been said, done, or even thought, and He will reward or punish each one accordingly (Psalm 28:4; 62:12; Romans 2:6; Revelation 2:23; 18:6; 22:12).

Also at this time, another book is opened, called the “book of life” (Revelation 20:12). It is this book that determines whether a person will inherit eternal life with God or receive everlasting punishment in the lake of fire. Although Christians are held accountable for their actions, they are forgiven in Christ and their names were written in the “book of life from the creation of the world” (Revelation 17:8). We also know from Scripture that it is at this judgment when the dead will be “judged according to what they had done” (Revelation 20:12) and that “anyone’s name” that is not “found written in the book of life” will be “thrown into the lake of fire” (Revelation 20:15).