@Wetech-Quantum, it sounds like you're looking for the low level details of what it's looking for in each file. You are correct about the OLE Links. The SE files are all compound files that have multiple data stores and streams, one of the data streams is named JSitesList and it has an encoding of the data stores that explain the referenced parts, components of an assembly or the drving part of a partcopy. To muddy the waters there's also sometimes a JReverseSitesList that contains links going the other way, I'm not 100% sure on this as I have not used it much, but they seem to get involved when there are sketches from one part using geometry from another part.
You didn't say if you had a purpose for knowing this or if you're just curious. Either way, this type of conversation might be better located in the Developer Forum. I spent a bunch of time working with JSitesList data stream and the JSite stores and the streams they contain when I wrote our CAD file indexing service.
If you cannot find a Solid Edge setting, confirm you have a file open of the type that will be affected.