I remember on WWE ‘12 for PS3 I was able to simply select a custom theme song from my music library Home Screen that I had imported from a thumb drive. I would also continue doing so by downloading music from RU-vid with a YT MP3 downloader from the PlayStation internet browser. All music would be downloaded and added to my music library.
You can search for the tutorial how to make the final boss entrance here on youtube (theres a complete tutorial) and download newest The Rocks Caw and The Final Boss image in your WWE 2k24 comunity, and then make the fireworks and lights as you want for last