How do I size a chain for a 1x SRAM GX Eagle AXS drivetrain?

Wrap the chain around the chainring and largest cassette cog, bypassing the rear derailleur. For hardtail bicycles, add two inner links and two outer links where the chain starts to overlap for a proper length of chain for your GX Eagle AXS drivetrain.
For full suspension bicycles, in order to size the chain, first compress the rear shock to the point in the travel where the rear axle is farthest from the bottom bracket. Deflate or remove the rear shock if necessary. Add one inner link and one outer link where the chain starts to overlap for a proper length of chain for your GX Eagle AXS drivetrain. See the user manual for installation for full details on the SRAM website service link.