public IEnumerable AppointmentLabelsSource { get; set; }

<DxScheduler DataStorage="@DataStorage">
    <Views>
        <DxSchedulerDayView DayCount="3"
                            TimeScale="@(new TimeSpan(1,0,0))"
                            WorkTime="new DxSchedulerTimeSpanRange(TimeSpan.FromHours(9), TimeSpan.FromHours(18))"
                            VisibleTime="new DxSchedulerTimeSpanRange(TimeSpan.FromHours(8), TimeSpan.FromHours(19))"
                            TimeIndicatorVisibility="SchedulerTimeIndicatorVisibility.Never">
        </DxSchedulerDayView>
        <DxSchedulerWeekView ShowWorkTimeOnly="true" />
        <DxSchedulerWorkWeekView ShowWorkTimeOnly="true" />
    </Views>
    <AppointmentCompactFormLayout Context="formInfo">
        <DxSchedulerSubjectFormLayoutItem></DxSchedulerSubjectFormLayoutItem>
        <DxSchedulerDescriptionFormLayoutItem></DxSchedulerDescriptionFormLayoutItem>
        <DxSchedulerLabelFormLayoutItem></DxSchedulerLabelFormLayoutItem>
    </AppointmentCompactFormLayout>
</DxScheduler>

@code {
    DxSchedulerDataStorage DataStorage = new DxSchedulerDataStorage() {
        // Specify appointment mappings here
        // ...
        AppointmentLabelsSource = LabelCollection.GetLabels(),
        AppointmentLabelMappings = new DxSchedulerAppointmentLabelMappings() {
            Id = "Id",
            Caption = "LabelCaption",
            Color = "LabelColor",
            // Uncomment the line below and comment the line above to specify other background options.
            //BackgroundCssClass = "BackgroundCssClass",
            TextCssClass = "TextCssClass",
            // Map the source object's custom field to the label's custom property.
            CustomFieldMappings = new List<DxSchedulerCustomFieldMapping> {
                new DxSchedulerCustomFieldMapping { Name = "MyCustomProperty", Mapping = "MyCustomField" }
            }
        }
    };
}

.label1-background {
    background-color: lightblue;
    border-color: blue;
}
.label2-background {
    background-color: lightgreen;
    border-color: green;
}
.label1-text {
    color: blue;
}
.label2-text {
    color: green;
}

public class LabelObject {
    public int Id { get; set; }
    public string LabelCaption { get; set; }
    public System.Drawing.Color LabelColor { get; set; }
    public string TextCssClass { get; set; }
    public string BackgroundCssClass { get; set; }
    public string MyCustomField { get; set; } // A custom field
}

public static class LabelCollection {
    public static List<LabelObject> GetLabels() {
        DateTime date = DateTime.Today;
        var dataSource = new List<LabelObject>() {
            new LabelObject() {
                Id = 1,
                LabelCaption = "Label One",
                LabelColor = System.Drawing.Color.LightBlue,
                // Uncomment the line below and comment the line above to specify other background options.
                // BackgroundCssClass = "label1-background",
                TextCssClass = "label1-text",
                MyCustomField = "Custom text for Label One",
            },
            new LabelObject() {
                Id = 2,
                LabelCaption = "Label Two",
                LabelColor = System.Drawing.Color.LightGreen,
                // Uncomment the line below and comment the line above to specify other background options.
                // BackgroundCssClass = "label2-background",
                TextCssClass = "label2-text",
                MyCustomField = "Custom text for Label Two",
            },
        };
        return dataSource;
    }
}

Storage.ResourcesSource = await ResService.GetResourcesAsync();
Storage.AppointmentLabelsSource = await LblService.GetLabelsAsync();
Storage.AppointmentStatusSource = await StsService.GetStatusesAsync();