How many meters of cable do you need for wiring in a one-room apartment?

Hello! Yes, the length of the lines strongly depends on the number of sockets and their connection diagram, if you lead a separate wire from the input panel to each outlet, then 100 meters may not be enough. In general, with so many electric points as you have, I think that it will not be enough.

To count - decide how you will install these sockets, judging by the number (up to 18 pieces), I think that you want to put blocks of 3-4 sockets in different corners of the room, roughly speaking where there will be some technique. If so, how will you connect these outlet strips? Let's say there is a separate cable from the junction box to each of the sockets or to each outlet block, and all the sockets from one block to this cable ...

Then you can mark the routes for future cable laying, calculate the total length by the length of these routes and the number of cables.

Also a question - do you assume the same cable for lighting? Then not enough under any circumstances.

I also recommend reading this article. https://samelectrik.ru/kak-soedinyat-rozetki-posledovatelno-ili-parallelno.html it will help you decide on the scheme, and this article with the footage - https://samelectrik.ru/skolko-nuzhno-kabelya-na-elektrosnabzhenie-doma-libo-kvartiry.html.