Getting and checking default value JVM HotSpot options by command line is simple.

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java -XX:+AggressiveOpts -XX:+UnlockDiagnosticVMOptions \
-XX:+UnlockExperimentalVMOptions -XX:+PrintFlagsFinal -version

Installed java version on my laptop:

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$ java -version
java version "1.8.0_192"  
Java(TM) SE Runtime Environment (build 1.8.0_192-b12)  
Java HotSpot(TM) 64-Bit Server VM (build 25.192-b12, mixed mode)

and above command prints in my case

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[Global flags]
     intx ActiveProcessorCount                      = -1                                  {product}
    uintx AdaptiveSizeDecrementScaleFactor          = 4                                   {product}
    uintx AdaptiveSizeMajorGCDecayTimeScale         = 10                                  {product}
    uintx AdaptiveSizePausePolicy                   = 0                                   {product}
    uintx AdaptiveSizePolicyCollectionCostMargin    = 50                                  {product}
    uintx AdaptiveSizePolicyInitializingSteps       = 20                                  {product}
    uintx AdaptiveSizePolicyOutputInterval          = 0                                   {product}
    uintx AdaptiveSizePolicyWeight                  = 10                                  {product}
    uintx AdaptiveSizeThroughPutPolicy              = 0                                   {product}
    uintx AdaptiveTimeWeight                        = 25                                  {product}
     bool AdjustConcurrency                         = false                               {product}
     bool AggressiveHeap                            = false                               {product}
     bool AggressiveOpts                            = false                               {product}
     intx AliasLevel                                = 3                                   {C2 product}
     bool AlignVector                               = false                               {C2 product}
     intx AllocateInstancePrefetchLines             = 1                                   {product}
     intx AllocatePrefetchDistance                  = 192                                 {product}
     intx AllocatePrefetchInstr                     = 0                                   {product}
     intx AllocatePrefetchLines                     = 4                                   {product}
     intx AllocatePrefetchStepSize                  = 64                                  {product}
     intx AllocatePrefetchStyle                     = 1                                   {product}
     bool AllowJNIEnvProxy                          = false                               {product}
     bool AllowNonVirtualCalls                      = false                               {product}
     bool AllowParallelDefineClass                  = false                               {product}
     ...

I just omitted the rest of the lines because it is too big, i.e. 877 options printed out there.