Is there already a product out there where you can write a keyword (or keywords) and be given the nearest section of a HUGE word document, access it to read or write, and then save it and it saves to the same section of that word document without having to open the whole document.

The reason I don't want to open the word document myself is because I sometimes write or makes notes consisting of 10,000 – 50,000 page+ word documents and I want a way to make these notes with sections so that I can access a specific section directly without having to convert to PDF first or wait 30 minutes to then be able to access the word document (and still have to deal with glitches and ctrl + f to find the thing I'm looking for over a long period).

Any references for how to approach this programmatically?