Applying dimensionality reduction on OneHotEncoded array
Following your example, you have different points in a 4-dimensional space. So, yes! you can use any dimensionality reduction technique, from PCA to UMAP.

In general, if your data is in a numeric format (and one-hot actually is), all the elements have the same dimensionality, and you don't have undefined values (NAN, inf), you can always use dimensionality reduction.