RetrieveAllEntitiesRequest req = new RetrieveAllEntitiesRequest();
            req.EntityFilters = EntityFilters.Entity;

            RetrieveAllEntitiesResponse resp = (RetrieveAllEntitiesResponse)service.Execute(req);

            foreach (var entity in resp.EntityMetadata)
            {
                //bind it with dropdown ETC
                entities.Items.Add(entity.LogicalName);

            }

Hope This Helped You Thanks For the Support , If Any query or suggestion , please comment below

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