Ender Dragon clutch: For this you must spawn a Ender Dragon and rely on its wings to bounce up.
Void clutch: You exit the map to the void and then it brings you back, therefore saving you for some time
Water Grasping Clutch: You place water and then swim into the small block

This is my guide for starting with PVP
PVP is a very large aspect of the game, with crazy Ender Dragon clutches to hitting techniques and versions with also debug things.
There are multiple modalities of PVP:
CPVP: Use ender crystals and respawn anchors to blast your enemies to death
CSPVP: Custom PVP, with player-made games
SPVP: PVP with a sword
APVP: PVP with axes
OPKPVP: PVP with diamond armor only
There are much more of them though.

Often, PVP involves hitting, do to the simple action press left-click on your mouse.
Although there is a thing called "Attack Speed" and a thing called "Combos"
The attack speed determines when you can do a strong(normal) attack, critical(strong+jump), knockback(any while running), and weak(spamclick)

Although then there are combos, they consist in keeping control of a enemy by hitting them a lot of times, this can be done with either weak, knockback, strong or critical, there is also a different type of combos which achieve specific things better(e.g. knockback) but are complex.

Here is a simple knockback combo: 2 weak 1 strong 2 knockback and then repeat.

Were skeletons your worst enemy once? Now they are your friends.
Using mobs for pvp is a little complicated. There are multiple purposes.
One of them is knockback, this is usually done with mobs that have a large hitbox and could push off the enemy. And you can deal damage through mobs, like by summoning a few ravagers on the enemy base.
Some servers have "team mobs" which attack only the enemy. On those servers it is easy to get guards and soldiers.
Although there are servers with "neutral mobs" which must ONLY be summoned near the enemy because they attack everyone.