Step 1- First go to your steam library

Step 2-right click on project zomboid and click on properties


Step 3- go to the general tab and click on startup parameters and type (-debug) without the brackets ofc

Step 4- now close out of the properties menu and back to your steam library, now just press play on project zomboid and Debug mode should now be activated

When you first click on the debug menu tab in game you will be greeted by this menu (look below)
on this menu one thing may have caught your eye, the cheat tab. Basically the cheat tab has many cheats, i shall list them below and what they do,
-invisible (makes you invisible)
-ghost mode (make no sound, zombies/players cant see or hear you)
-noclip (you can walk through walls and other objects like a ghost)
-fast move (you can move at a set speed)
-timed action instant (doing things like picking things up is now instant)
-unlimited carry (can carry unlimited amount of items without taking any damage)
-unlimited endurance (cant get exerted)
-unlimited ammo (cant run out of ammo, kinda self explanatory)
-build cheat mode (Building and construction cheats)
-known all recipes (You know all recipes for everthing without having to read the books)
-farming cheat (cheats for crops, growth and farmland)
-health panel cheat (healing cheats and visual cheats, eg making you arm look bloody)
-mechanics cheat (cheats for mechanics like car, repairs and fixing car parts)
-moveable cheat (move and place things like tvs instantly
-loot zed (zombie loot cheat)
-brush tool (no idea you'll have to try it)
-god mode (makes you invincible ofc)

that is all about the cheat tab, cheats in it and what they do/alter.