How to make custom dimension exactly look like the overworld

Note: I am new to modding for Minecraft.

I am trying to recreate a time travel dimension, I guessed it uses custom dimensions so that's why it is about dimensions. The effect I am trying to achieve

Now I made two dimensions, Past far and past.

Now past is like the overworld, and Past far is a stone/rock-like version of the past. But past is not like the overworld in any way. how can I achieve this?

Also, I have looked on google on how to do this but there is only one post and that is about version 1.7.10.

I am not sure but since 1.16.5 I think you have to use JSON files.

Thanks.

Edited January 24, 20223 yr by Cookie_roll12