here is 3 1.14.4 commands for minecraft
1. /execute command.
Just go /execute at (player name) run (your command) in a repeating command block.
For example /execute at @p run setblock ~ ~-1 ~ minecraft:yellow_wool. which makes yellow wool appear under the nearest player.
2. The special mobs.
Go to Minecraft Tools and you will find a mob generator and a few other things, click on the generator. customize your mob, then copy the command into a command block and activate it. if you did a spawn egg you will get a spawn egg, if you did the default (summoning) you will summon a mob. if you pick a spawner beneath the command block there will be a spawner. And there’s your mob!
3. Potion Maker
Go to Minecraft Tools and go to the potion generator. customize your potion, then get a command block then past the command and activate it and get your potion!