To simplify the expression \((6^2)^4\), we can use the power of a power property of exponents. This property states that \((a^m)^n = a^{m \cdot n}\).
Applying this property:
\[ (6^2)^4 = 6^{2 \cdot 4} \]
Calculating the exponent:
\[ 2 \cdot 4 = 8 \]
Thus, we have:
\[ (6^2)^4 = 6^8 \]
The simplified expression is:
\[ 6^8 \]