Default FiveM Ace System:
add_ace identifier.steam:steamidhere "the.permission.name.you.want" allow/deny
if IsPlayerAceAllowed(playerSource, "the.permission.name.you.want")

Better (SQL & lightweight) Permission System - PermissionsPro
FiveM Forum: https://forum.cfx.re/t/permissionspro-a-lightweight-sql-permissions-resource-for-fivem/1502521
Github: https://github.com/CodineerDigital/PermissionsPro

Command: /permissionspro  
Checking: Just as in default FiveM to make it more compatible with
other resources.