The scientific discoveries prove that the Kaaba is located in the center of the land of the earth, as it is mentioned in some traditions. But it should be noted that the center of the earth does not mean the core of it.
"The Kaaba is the center of the earth" is a saying of the Prophet (PBUH), [1] but center of the earth does not mean the core of it. The scientists have discovered that if we consider the earth as a flat earth we will miraculously discover that the Kaaba is the center of the land of the earth. [2] From the time of Adam (PBUH), the first constructor of the Kaaba, till now, it has been received many attention from adherents of different religions even polytheists. The Qur'an says: "Indeed, the first House [of worship] established for mankind was that at Bakkah [i.e., Makkah] – blessed and guidance for the worlds." [3]
[1] Uyon-e Akhbar Al-Reza, vol 2, page 182-183.
[2] https://www.theflatearthsociety.org/forum/index.php?topic=64715.0.
[3] Chapter3, verse 96. إِنَّ أَوَّلَ بَيْتٍ وُضِعَ لِلنَّاسِ لَلَّذِي بِبَكَّةَ مُبَارَكًا وَهُدًى لِلْعَالَمِينَ