Can someone restring a violin to be viola?

While the strings of a viola and a violin are similar in pitch (C, G, D, A), viola strings are typically longer and tuned lower. Because of this, the neck of a viola is also typically longer than a violin neck.

Additionally, violas' and violins' bodies are slightly different with respect to their shapes and measurements.

Because of these differences, a violin cannot be simply restrung and "become" a viola.