there is a site where you can make all the commands you want, and it's very useful (there isn't all the commands but many) : https://www.gamergeeks.net/
There is a few funny things about minecraft pvp, you can train your pvp skills in pvplegacy, this is a minecraft server when you can create your own pvp kits, thats awesome for training the parts of the pvp one by one, like the aim, the reach, etc...
a very known mechanic in pvp is attribute swapping, and it's when you attack the ennemy at the same tick you swap your slot for something else, it combines the enchantments, the cooldown and the damages of the 2 things, for example, if you swap an ennemy while falling with a sword to a mace, the ennemy can be one or two shotted instead of three. This is important because of the time, if you let time go he can eat food and regen. An other exemple is if you attribute swap between 2 netherite sword it will do a loot of damage. But we can manipulate the minecraft ticks other ways...
You can drop an item and swap to another slot at the same tick. This create a ghost item in your hand (the real item is dropped in the ground), the others players can't see the ghost items, the ghost items can't be throwed like enderpearls, windcharges etc... If you drop ghost items they will disapear (also if you put them in a chest or simply move them in your inventory). But, they can be useful, if you have ghost blocs per exemple, you can place them a tick before minecraft make them disappear, so with the right timing you can climb walls with ghost blocks or just place them under you to have more speed. There is also the ghost trident, if you make a ghost trident anchanted with riptide, you can use the riptide enchantment with it, and the others person don't see your ghost trident. You also can make a ghost armor but it do nothing unless you enchant it (i don't tried yet), to put a ghost armor just right click on it, it moves the item ito the armor slot without taking the item (otherwise it disapear). The elytra can be ghosted but it glide only one tick, it can be useful when you're falling to slow your fall (by spam-clicking the spacebar) even if you take the same fall damage you can search a way to break your fall.
You also can manipulate the minecraft ticks by doing an action (like attack or eating) and open your inventory at the same tick for organised it, it's more used to eat while orginasing your inventory in a fight, it can be very useful if you're in cpvp, when you totem you can eat at the same time.
The attack gauge is actually inaccurate, you deal 100% of your damages when you attack if you hit when the gauge is filled at 84.8%
for break your fall there is the normals items like the water bucket, the hay bale, cobweb, etc... But minecraft is coded like it calculates the distance from which you descend and don't care about the speed, thats why sometimes in elytra you take fall damage even slowly. To clutch a fall with no special items, you have to go up -at least one tick- before hitting the ground, with windcharges for exemple, or even damage of a mob who gives you knockback
if you want to change the site : discord link