Firstly you need to add NuGet feed for Sitecore 9.3
Install-Package Sitecore -Version 9.3.0 -Source https://sitecore.myget.org/F/sc-packages/api/v3/index.json
Then you need to go Manage Nuget Package
and search DLL name then click on update
Firstly you need to add NuGet feed for Sitecore 9.3
Install-Package Sitecore -Version 9.3.0 -Source https://sitecore.myget.org/F/sc-packages/api/v3/index.json
Then you need to go Manage Nuget Package
and search DLL name then click on update