Not always, but sometimes large IT companies may find it difficult to maintain a high level of work quality and communication with clients. It may also be the case that giants will not find your small project attractive and will not want to handle it at all. This is not a rule, but you should keep it in mind when choosing a software house. On the other hand, teams of several people usually work on one project. Much more important than the number of employees is the number of case studies from various industries that are in the portfolio of a given IT company.