Comment by secondcoming

Here's a paper reviewing the various choices, that is often mentioned in discussions around data structures for text editors:

https://www.cs.unm.edu/~crowley/papers/sds.pdf

VSCode uses a piece table (https://code.visualstudio.com/blogs/2018/03/23/text-buffer-r...).

Gap buffers are the other classic option, and there are others too, e.g. piece tables.

Most certainly: gap buffers, piece tables, and line arrays are also popular choices.