Mod similar to origins mod but with random potion effects

I want to create a custom mod where when you spawn, you can choose a potion effect from 3 randomly chosen potions that you keep for the entire time that you play (similar but also different to the origins mod) that can also become better based on the achievements you get such as free the end or other essential but also a tad bit challenging achievements. I'm pretty new to modding and I'm not super good, how could I try and do this? I need help with the assigning, the assigning GUI, finding what the player's assigned effect is when they join the world, and the upgrades of the effects when they get achievements.