@Asier , If you want to create .net Framework 4.8 app, you could Add a new Project -> WPF App(.NET Framework)->Choose .NET Framework4.8.
If you want to use .net 6.0, I recommend that you use vs2022 Preview to do it.
Please click Add a new Project -> WPF App->Name the Project->Choose .NET 6.0.
Hope this could help you.
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