you have to download datapack to specific world for this - all you need is to create folder in datapacks folder - C:\Users\Egor\AppData\Roaming\.minecraft\saves\(your world's name)\datapacks , name it whatever you like to but you also have to create a lot of advancements or functions commands and it takes a lot of time so you can download it from https://www.planetminecraft.com/texture_pack/blazeandcave-s-advancements-pack-1-12/ ,also the benefit of it is that when you getting specific advancement , in function reward flolder creator of the datapack already did that it saying which reward you got and when is advancement pack is installed to the world, so that will make this much easier. Read whole blog and follow instruction for example like they said you have to type /scoreboard players set Reward Reward 1 command inside your minecraft world where you want to make it.

WARNING IF YOUR FUNCTION DOES NOT WORK AFTER DOWNLOADING https://www.planetminecraft.com/texture_pack/blazeandcave-s-advancements-pack-1-12/ PLEASE CHECK JSON FILE OF FUNCTION NAME AND ADVANCEMENT AND THAT SPELLING IS CORRECT TO CONNECT THEM, THERE IS MISTAKES IN SPELLING LIKE MOB_KILLED ADVANCEMENT IS
"rewards" : {
"function" : "mystuff:monster_hunter"
}
WHEN IT FUNCTION IS monsters_hunted.mcfunction SO IT SHOULD BE
"rewards" : {
"function" : "mystuff:monsters_hunted"
}
PLEASE PAY ATTENCION ON THAT.

After downloading read instruction "readme" inside the zip file and follow instructions

after you learned how it works by instructions you can just change the functions advencements does as reward , i recommend you Atom text editor for this because it has tool to show if the text correct and sometimes item's id which you can put - atom.io/

when you inserted bac_advancements folder to your datapacks go to >data>minecraft>advancements>chose any folder>chose any advancement>open with Atom text editor

after read which function connected to this reward , if you cant find function press cnt+f inside the Atom text editor and search for function

remmember this connected function

go again to your world's datapack bac_advancements>data>bc_rewards>functions>find function name which you memorized around this folders with mcfunction files

ones you founded, open it with Atom and delete everything if you dont like which command it does or add below execute if score Reward Reward matches 1 run (your command) without ()

you can also run infinity number of commands at the same time just by adding more execute if score Reward Reward matches 1 run (your command) belower

now in your minecraft 1.13.1 version this function works as command which activated when you got specific advancement you chosed , more options and advanced tools
about it you can find on this blog - www.planetminecraft.com/blog/minecraft-s-advancements-more-advanced-than-you-might-think/

if there something not working after this steps,comment for taking action with problems because
i will be happy to help as much i can comment for taking action with problems

if you want to learn more about execute and detailed minecraft 1.13 version changes you can whatch this video https://www.youtube.com/watch?v=uO41sptfGt8&t=174s and read description to find new commands which you can trigger/set/execute this advancement or do anything you want