Do Sims need to get to level 10 in a skill for challenges to show?

Check the skills in the Sims skill panel. Each individual skill will have different challenges that require different levels of skills or different achievements to complete. For example when a sim knows 28 recipes that will complete a skill challenge. Making 25 ice sculptures will complete another skill challenge and that sim will then be able to make ice sculptures that never melt. Each skill has one or more challenges.

"ItsMeThatGuy;d-999092" wrote:
I use a instant skill challenge mod by HelloSims and I was hoping if the Sim needs level 10 skill to finish the skill challenges. As I don't know if other Sims will also finish the challenge and, well, put a disadvantage to my Sim. They said in a page that you need to master a skill to open skill challenge. I'm just wondering if other Sims can also finish skill challenges as well.

You will be level 10 by the time you finish all the skill challenges, but you don't need to be level 10 for them to start. IMO, skill challenges are very much like Sims 4 aspirations, but a much better system as you're not tied to doing things in a certain order. Non active sims can probably do skill challenges, at least with a story progression mod, but they're hard enough to complete that it's unlikely that they will finish many.