OperationIdEnricher.cs

using System;
using Serilog.Core;
using Serilog.Events;

// .Enrich.With(new OperationIdEnricher())
class OperationIdEnricher : ILogEventEnricher
{
    public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
    {
        if (logEvent.Properties.TryGetValue("RequestId", out var requestId))
            logEvent.AddPropertyIfAbsent(new LogEventProperty("operationId", requestId));
    }
}