In order to actually get a skyblock world, you currently must go to the world generation options, and select the garden of glass world generator.
This is a relatively light weight skyblock modpack, where my goal is to keep the mod count below a hundred content-adding mods, while still having as much content as possible.
I have done my best to keep the modlist limited to mods on aternos, so I can play it with friends.
If you want a mod added, suggest magic or Quality of Life mods, as that's what I want the most. The main mod in this modpack is botania, thaumcraft and (magical) psi.
Botania, for power, ores, the garden of glass (where this started), and pretty much all it's content.
Thaumcraft for automation (golems).
PSI, because I like the concept of making my own spells.
It also has resizing potions as a nice QoL mod, as you can make tiny houses (using chisel+bits), get in tiny places, etc.
For servers and to suggest mods, join the discord.
Report issues on the discord/on the issue tracker, and have fun!
(Btw, the challenge of this modpack is that occasionally, you get a task that seems unachievable because of the fact that I don't have the mods required for it, but then you play around and find a solution.)