Team size and code quality are two different terms but they are inter-linked to each other in the development of a software. Before we find out the relation between the two, we need to understand both these terms.
Team Size:
To accomplish a task that has complexity, risk, maintenance, is huge and is professional, you require a group of highly skilled individuals that are expert in their field of job, are energetic, interdependent and have good tendencies to collaborate with each other. This group of people who share the same goal but have different tasks to execute form a team. The size of a team depends on the nature of work.
Code Quality:
Code quality is calculated based on two principles. The usefulness of the code on long term basis and the maintenance of the 
code on long term basis. A code is said to be of high quality if it doesn’t worn out easily, has the tendency to expand, is open sourced, robust and can easily be maintained.
Team size is an important aspect when we want to accomplish an ambitious task that is big in size and is of complex nature. But we also need to understand that there are many factors that contribute in building a great team. Merely forming a team won’t work unless we assign them definite task that is synchronized with the shared goal.
Does the Quality of Code depends on Team Size?
There is no definite answer to this question but it definitely depends on the team we chose, how we assign them task and how we synchronize the whole team with each other to accomplish the shared goal. To accomplish the task of building a quality code, you need to have a team of 4-5 people that have high focus on their job. If the size of the code is big or it is complex then one can form a group of 3-4 teams.
Forming a large team doesn’t really works because the focus somewhere deviates because a large will definitely have differences and the collaboration also doesn’t fits in.
Conclusion:
The code will have quality on when the coder is focused on the work and understands his/her job well. A small team with focused individuals will do much better than a huge team which is deviated from the goal. As long as the individuals know their job and they are synchronized with each other, the code will definitely have a good quality.
