Check out example codes for "c# expression func automatically select return type". It will help you in understanding the concepts better.

Code Example 1

// If property is something like an int or double and you want an object,
// you need to manually convert it to an object via another expression.
var parameter = Expression.Parameter(typeof(T));
var body = Expression.Property(parameter, propertyName);
var converted = Expression.Convert(body, typeof(object));
return Expression.Lambda<Func<T, object>>(converted, parameter);

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