Accordion for version 17.3.29.

@using Syncfusion.EJ2.Blazor.Navigations

<EjsAccordion DataSource="@AccordionItems" ModelType="@typeof(AccordionData)">
    <AccordionTemplates>
        <HeaderTemplate>
            <div>@((context as AccordionData).EmployeeName)</div>
        </HeaderTemplate>
        <ItemTemplate>
            @{
                AccordionData ContextData = context as AccordionData;
                <div>
                    <div><b>Employee ID: </b>@ContextData.EmployeeId</div>
                    <div><b>Designation: </b>@ContextData.Designation</div>
                </div>
            }
        </ItemTemplate>
    </AccordionTemplates>
</EjsAccordion>

@code{
    List<AccordionData> AccordionItems = new List<AccordionData>()
{
            new AccordionData
            {
            EmployeeId = 1,
            EmployeeName = "Laura Callahan",
            Designation = "Product Manager",
            },
            new AccordionData
            {
            EmployeeId = 3,
            EmployeeName = "Andrew Fuller",
            Designation = "Team Lead",
            },
            new AccordionData
            {
            EmployeeId = 4,
            EmployeeName = "Anne Dodsworth",
            Designation = "Developer"
            },
            new AccordionData
            {
            EmployeeId = 5,
            EmployeeName = "Nancy Davolio",
            Designation = "Product Manager"
            }
    };

    public class AccordionData
    {
        public string EmployeeName { get; set; }
        public int EmployeeId { get; set; }
        public string Designation { get; set; }
    }
}