ConnectToCrm.cs

var crmClient = new CrmServiceClient(ConfigurationManager.ConnectionStrings["D365"].ConnectionString);
if (crmClient.IsReady)
{
   
    using (var ctx = new OrganizationServiceContext(crmClient))
    {
        var result = ctx.CreateQuery<Contact>()
            .Where(a => a.FirstName == "Jan")
            .Select(a => new Contact
            {
                Id = a.Id,
                FirstName = a.FirstName
            })
            .ToList();

        Console.WriteLine(result.Count);
    }                
}