https://medium.com/swlh/the-comprehensive-8pt-grid-guide-aa16ff402179
Left Nav Bar UI Design: Setting Up Your Grid Layout in Figma
https://help.figma.com/hc/en-us/articles/360040450513
You can only apply layout grids to frames. This could be a top-level frame, or a frame nested within another frame.
You can apply a layout grid to any frame. Remember that components are also frames, so you can apply them to components too.
https://www.figma.com/blog/everything-you-need-to-know-about-layout-grids-in-figma/
https://www.behance.net/gallery/79083769/12-columns-Pixel-Perfect-Grids-for-Figma