SystemUpdate()?

Created by, Modified by, Created and Modified.

Display Name Vs Internal Name 

• Created by    >  Author
• Modified by  >  Editor

SharePointPnPPowerShellOnline\Set-PnPListItem -List "EMp" -Identity "5" -Values @{"Editor" ="raghu@peakinders.org"} 

SharePointPnPPowerShellOnline\Set-PnPListItem -List "EMp"  -Identity "5" -Values @{"Modified"=$olddate}-SystemUpdate

• Modified and Modified By fields changed 

• No new version (You can pass false to the method just to enable generating a new version)