While some translators treat the verse as speaking about creating the earth, others like the NKJV and JPS more accurately render אוֹתָ֛הּ simply as "it."
Thus says the LORD who made the earth, the LORD who formed it to establish it—the LORD is his name (ESV)
Thus says the LORD who is planning it,
The LORD who is shaping it to bring it about,
Whose name is LORD. (JPS)
כֹּֽה־אָמַר יְהוָה עֹשָׂהּ יְהוָה יֹוצֵר אֹותָהּ לַהֲכִינָהּ יְהוָה שְׁמֹֽו
The emphasis is on the LORD as redeemer and restorer of His creation.
Marvin A. Sweeney says:
A second set of oracles continues the focus on the coming restoration, but emphasizes the House of David and the Levitical priesthood will also be part of God's everlasting covenant with Israel. The divine oracle begins with a hymnic passage that relates God's role as creator. The interest in God's plans appears frequently in Isaiah as a means to explain disaster by asserting that God plans from the beginning to bring deliverance after a period of punishment (Isa. 10:13; 14.27; 28.23-29; 53.11).1
The "it" is the restoration of Israel.
After the LORD corrects the nation by allowing the Babylonians to destroy Jerusalem and the Temple which is the place of His Name, He will restore the House of Israel and the House of Judah (33:14). This restoration comes with a promise paralleling the one made with Abraham:
As the host of heaven cannot be numbered and the sands of the sea cannot be measured, so I will multiply the offspring of David my servant, and the Levitical priests who minister to me. (Jeremiah 33:22 ESV)
I will surely bless you, and I will surely multiply your offspring as the stars of heaven and as the sand that is on the seashore. And your offspring shall possess the gate of his enemies
(Genesis 22:17 ESV)
1. Marvin A. Sweeney, The Jewish Study Bible, Oxford University Press, 2004, p. 995