The Bible does not say the good Lord made the Earth 6,000 years old.
It doesn’t directly say 6000 years, but if you count the years of the generations from Adam to Christ, you have a pretty good idea of the actual age of the earth. Amazingly, that’s exactly what the Jews do with their calander and while I may quibble with a few things, I agree with them that earth is not over 6000 years old.