There is an environment variable named ASPNETCORE_ENVIRONMENT that you can change. There is a link here where you can read different suggestions. https://stackoverflow.com/questions/41546943/how-to-set-aspnetcore-environment-to-be-considered-for-publishing-an-asp-net-cor

I use Web.config with transformation on publish.

Web.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <system.webServer>
        <aspNetCore processPath="dotnet" arguments=".\MyProject.Web.dll" hostingModel="InProcess" stdoutLogEnabled="true" stdoutLogFile=".\logs\stdout">
            <environmentVariables>
                <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Development" />
            </environmentVariables>
        </aspNetCore>
    </system.webServer>
</configuration>

Web.Release.config

<?xml version="1.0"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
    <system.webServer>
        <aspNetCore>
            <environmentVariables xdt:Transform="InsertIfMissing">
                <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Production" xdt:Transform="SetAttributes" xdt:Locator="Match(name)" />
            </environmentVariables>
        </aspNetCore>
    </system.webServer>
</configuration>

and then it would use the appsettings.Production.json.

Do you use the same database when you deploy?

If not, is the database you then use maybe empty?