With this plugin you can easily create your own custom commands.
Wiki on https://dev.bukkit.org/projects/customcommand

ONLY 1.21 AND UP
Tested: 1.21.4, 1.21.5
Couldn't test 1.21 cuz it doesn't support my java version :/

This is the spigot version, for paper, look on modrinth one of the links below

Links:
Modrinth: https://modrinth.com/plugin/ccmd
Bukkit: https://dev.bukkit.org/projects/customcommand
Github: github.com/Ontey6/CustomCommand