The fact that 1+1=2 is baked in to the structure of set theory and logic and stems from the most basic rules of how things are structured. It can be derived from the definition of a topological space, it can be derived from the axioms of category theory and type theories and it even shows up in paraconsistent logics.
Ignoring SJW misunderstandings of goat-herder education, in order to have an alternate universe where 1+1 is not 2 you would need to start with some incredibly different logic systems. What would that look like?