My range bag standard kit:
- Eye pro (two pairs, one clear one tinted)
- Electronic muffs + backup foamies
- Chamber flag
- Small first aid kit including a CAT tourniquet and chest seal (this has been the biggest change over the last two years — I didn't use to carry TQ/seal and now I always do)
- Zip ties, electrical tape
- Stapler, targets, pen for logging
- Snacks and water
For guns: two magazines minimum per firearm, factory-fresh defensive ammo in addition to practice ammo, notebook for dope/zero data.
The medical kit is the biggest "everyone should do this" change I'd push for. You're meaningfully more likely to use a TQ at the range than a gun.