比如Sum的Method选项值 （Automatic, "HypergeometricTermFinite",
"HypergeometricTermGosper", "HypergeometricTermPFQ",
"HypergeometricTermZeilberger", "LevelCounting", "Logarithmic",
"PeriodicFunction", "PolyGammaHypergeometricSeries",
"PolyGammaIntegralRepresentation", "PolyGammaSumByParts",
"Polynomial", "PolynomialExponential", "PolynomialTrigonometric",
"Procedural", "QHypergeometricTermGosper",
"QHypergeometricTermZeilberger", "QRationalFunction",
"RationalExponential", "RationalFunction", "RationalTrigonometric",
"TableLookup"）
有这样的命令吗？

没有通用方法。有兴趣的话可以沿着Stackexchange的Undocumented标签读一读。另，虽然文档里没写的选项值不少，但从实践来看，这些选项大都没有手动设定的价值……