<PackageReference Include="System.Reflection.Emit" Version="4.6.0-preview8.19405.3" />

FieldBuilder

public sealed class FieldBuilder : FieldInfo
Defines and represents a field. This class cannot be inherited.
public void SetConstant(object defaultValue)

Sets the default value of this field.

public void SetCustomAttribute(ConstructorInfo con, byte[] binaryAttribute)

Sets a custom attribute using a specified custom attribute blob.

public void SetCustomAttribute(CustomAttributeBuilder customBuilder)

Sets a custom attribute using a custom attribute builder.

public void SetOffset(int iOffset)

Specifies the field layout.