Corollary 7.1.7.11. Let $\operatorname{\mathcal{C}}$ be an $\infty $-category, let $B$ be a simplicial set, and let $f: K \rightarrow \operatorname{Fun}(B, \operatorname{\mathcal{C}})$ be a diagram. Assume that, for every vertex $b \in B$, the diagram
\[ K \xrightarrow {f} \operatorname{Fun}(B,\operatorname{\mathcal{C}}) \xrightarrow { \operatorname{ev}_ b } \operatorname{\mathcal{C}} \]
has a colimit in $\operatorname{\mathcal{C}}$. Then $f$ can be extended to a levelwise colimit diagram $\overline{f}: K^{\triangleright } \rightarrow \operatorname{Fun}(B,\operatorname{\mathcal{C}})$.