Just dropping these here for later reference.
https://www.gamedeveloper.com/design/multiplayer-level-design-in-depth-part-1-the-specific-constraints-of-multiplayer-level-design
https://www.gamedeveloper.com/design/multiplayer-level-design-in-depth-part-2-the-rules-of-map-design
https://www.gamedeveloper.com/design/multiplayer-level-design-in-depth-part-3-technical-constraints-and-accessibility
https://book.leveldesignbook.com/