Do you want to create a SQL Server connection in your app?
Do you want to know which Authentication type does the existing SQL Connection use?
If you want to see the Authentication type under the "Details" tab of the existing SQL Server connection, I afraid that there is no way to achieve your needs in PowerApps currently.
Currently, the Authentication type property is not available under the "Details" tab of the existing SQL Server connection. If you would like this feature to be added in PowerApps, please consider submit an idea to PowerApps Ideas Forum: