use -V for the option prefix, which suggests "verbose" or "view"...

... for when you want to tweak output (as opposed to compiler behavior).

as suggested in scala#16011 (comment)

Author: mpollmeier

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -149,6 +149,7 @@ private sealed trait VerboseSettings:
   val Vprofile: Setting[Boolean] = BooleanSetting("-Vprofile", "Show metrics about sources and internal representations to estimate compile-time complexity.")
   val VprofileSortedBy = ChoiceSetting("-Vprofile-sorted-by", "key", "Show metrics about sources and internal representations sorted by given column name", List("name", "path", "lines", "tokens", "tasty", "complexity"), "")
   val VprofileDetails = IntSetting("-Vprofile-details", "Show metrics about sources and internal representations of the most complex methods", 0)
+  val VreplMaxPrintElements: Setting[Int] = IntSetting("-Vrepl-max-print-elements", "Number of elements to be printed before output is truncated.", 1000)
 
 /** -W "Warnings" settings
  */
@@ -231,7 +232,6 @@ private sealed trait XSettings:
   val XprintSuspension: Setting[Boolean] = BooleanSetting("-Xprint-suspension", "Show when code is suspended until macros are compiled.")
   val Xprompt: Setting[Boolean] = BooleanSetting("-Xprompt", "Display a prompt after each error (debugging option).")
   val XreplDisableDisplay: Setting[Boolean] = BooleanSetting("-Xrepl-disable-display", "Do not display definitions in REPL.")
-  val XreplMaxPrintElements: Setting[Int] = IntSetting("-Xrepl-max-print-elements", "Number of elements to be printed before output is truncated.", 1000)
   val XverifySignatures: Setting[Boolean] = BooleanSetting("-Xverify-signatures", "Verify generic signatures in generated bytecode.")
   val XignoreScala2Macros: Setting[Boolean] = BooleanSetting("-Xignore-scala2-macros", "Ignore errors when compiling code that calls Scala2 macros, these will fail at runtime.")
   val XimportSuggestionTimeout: Setting[Int] = IntSetting("-Ximport-suggestion-timeout", "Timeout (in ms) for searching for import suggestions when errors are reported.", 8000)

compiler/src/dotty/tools/repl/ReplDriver.scala

@@ -115,7 +115,7 @@ class ReplDriver(settings: Array[String],
     compiler = new ReplCompiler
     rendering = new Rendering(
       classLoader, 
-      maxPrintElements = rootCtx.settings.XreplMaxPrintElements.valueIn(rootCtx.settingsState)
+      maxPrintElements = rootCtx.settings.VreplMaxPrintElements.valueIn(rootCtx.settingsState)
     )
   }