Hello,
I currently utilize Adonis Admin in my game, and I have seen other games prevent players from using commands on “others,” “all,” and etcetera. I do not have any experience in programming, and I was wondering if someone could help me out. I would greatly appreciate it. 
This is nowhere the right place to ask for the functions of a player made admin engine, still there is not any code provided, so we can’t help you well. As Adonis is widely used, they probably own some sort of group which can provide you some help.
Hopefully, this message isn’t off-topic. But if you join Adonis discord server, they could assist you with this problem. As well of the devforum, they don’t talk about somebody-made adonis.
Here is there Roblox group. ~ Roblox Group ~ I see the other guy said a discord server I will try to find that as well. I too want help with some adonis stuff. If I find the discord I will post it here.