In October 2020 I published Working with Modular Baseline Grids, a tutorial showing how I create modular grids in Adobe InDesign from a blank document.
The tutorial covers the full set-up – from the baseline grid and margins to creating rows and columns and building out the typography from that underlying foundation.
The tutorial also looks at the Colours Grid System Series – which includes layouts for A4, US Letter, A5 and 6 × 9 inch formats. I discuss grid structure, margins and paragraph styles, and show how the layouts can be used.
The Colours files are available to download free, or pay what you want, on Gumroad.
If you’re learning how modular grids work, I’d suggest watching the tutorial first and then opening one of the files in InDesign. Having the finished layout in front of you makes it much easier to see how the different parts of the grid work together.