Isaiah 11:6 speaks of the millennial reign.
That is on Earth, not the “new Earth.”
Be that as it may, Isaiah 60:21 states, “Then all your people will be righteous and they will possess the land forever. They are the shoot I have planted, the work of my hands, for the display of my splendor.”
Clearly, the vast majority of the righteous will remain on planet earth, as indicated by the phrase ‘they will possess the land forever’. God’s original purpose for mankind has not changed since Adam.
Revelation 20:11 And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them.
2Peter 3:
[7] But the heavens and the earth, which are now, by the same word are kept in store, reserved unto fire against the day of judgment and perdition of ungodly men.
[8] But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day.
[9] The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
[10] But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.
[11] Seeing then that all these things shall be dissolved, what manner of persons ought ye to be in all holy conversation and godliness,
[12] Looking for and hasting unto the coming of the day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat?
[13] Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness.