Many mods have configurability in sandbox options when creating a game. Some of them I recommend not playing without changing. Briefly scroll down and check highlighted categories primarily for things I think most people want to change for sure.
If you already started a game you should have sandbox options available when right clicking in the world thanks to one of the mods, may require debug mode.

This is the repair mod that is essentially a "cheat". It lets you repair any car parts up to 90% durability for free, costing only time. It scales with your mechanics stat and requires some skill before you can do it.
(this allows repairing parts up to 90%)
(this makes standard vehicles require mechanics 4, heavy 5, and sports 6. you can type in -4 to make it 0/1/2 instead or 4 to makes it 8/9/10 instead.

Here I simply recommend enabling the keep bags equipped option on both mods, as there is already another mod letting you exercise with your bags on, you have to enable these to also keep your bags on for the treadmill and benchpress.
Currently the treadmill is quite a bit worse than just doing situps for fitness xp, but there is no tweak for it, only for the strength and sprinting bonuses. The treadmill currently gives fitness, strength, and sprinting xp.

Like dynamic traits, this mod is another way to minmax and change traits after character creation. It lets you find magazines for many traits that you can use to learn these traits. By default, if you have the negative versions of any of these the magazines will only remove the negative. The first check box allows you to instead turn the negative into the positive with them. You can also enable or disable any of the magazines here.

This is my favorite gear pack and thus I changed most of the values here to my liking. Patriot/Defender/Vanguard just refer to light medium and heavy armor pieces of stated colors. I increased black gear chances quite a bit in secret bases and overall lowered chances for desert and snow gear.
[Black 4/2/1] [Desert 2/1/0.5] [Green 8/4/2] [White 0/0/0]
[Black 0.5/0.1/0.05] [Desert 0.5/0.4/0.2] [Green 1.5/1/0.5] [White 0.5/0.4/0.2]
[Black 6/8/4] [Desert 0/0/0] [Green 2/4/2] [White 0/0/0]

One of my favorite mods as I am a dirty pack rat. The default settings are not too overpowered but keep in mind this lets you upgrade all the different bags you are wearing (ANY WEARABLE CONTAINER) even bandoliers. I buffed the values because I really want to carry whatever I want and feel rewarded for collecting upgrades and leveling tailoring to 10 (lets you create military upgrades). (All wearables have 2 upgrade slots.)
(Backpacks get above value plus this value for four slots.)
This means there is a flat bonus of 3 instead of 2. Default of 2 means that on small bags, military bag upgrade is the same as leather, which is disappointing. It does however let you vastly buff small containers.

A mod only really necessary if you intend to respawn a new character on death or for playing on servers in the future. You can configure the skill recovery rates here.

The default settings make almost all zomboids in mil base and secret bases wear UCP (white camo) gear, vastly outweighing other spawn chances and especially KATTAJ, which I prefer. The first setting that is set to [20.0] should be lowered drastically to match the other values.

You can change the effectiveness of the skill which makes all timed actions faster when leveling it. However by default I think it is okay as it is extremely difficult to level and gives reduced xp gains down to nil if you just try to spam actions on fast forward.