This will of course vary between advisors and research groups, but I can discuss the differences I’ve seen in general between large and small labs. There are some differences which will be an advantage or disadvantage based on your personal preferences/working style, and others that can have a direct impact on research.
As a PhD student I was a part of a large academic lab, where we had approximately 20 people including Masters, PhDs, and post-docs plus an additional array of more temporary undergrads. As a large group, we had a variety of projects ongoing, with some involving small teams working on the same or similar topic. Being in a small team suited me, personally, quite well. The multiple ongoing research directions allowed me to also expand my knowledge base through informal discussions and during lab meetings, in addition to providing easy opportunities for collaborative research in smaller side projects through my degree. Older/more advanced students and post-docs were also a font of knowledge and advice for my own research problems. As a large group, we had a good amount of resources, monetary and otherwise, which was a definite bonus.
However, as a manager of a large lab, my advisor had little time for much personal attention or anything besides general direction. As such, it was much more difficult finding my research ‘footing’. After the first few difficult years, though, I flourished with the relative research freedom. From discussions with friends in much smaller labs, the involvement of their advisors was much higher and ranged from, in the beginning, weekly specialized task lists, to working side-by-side in the lab.
Once again, this will be heavily dependent on the people involved, but it is difficult to expect the same amount of interaction from an advisor who must split their attention n times more ways. I know a few who had co-advisors (where one was more established, one newer) to balance the issues I discussed (particularly the lack of funding/resources with the latter), but each option has their own advantages and disadvantages. Being co-advised is definitely no exception; getting them to agree to go in the same research direction can be simultaneously frustrating and terrifying.
With a small lab you may indeed be missing something research-wise, but your training in the ability to do research and your knowledge in your particular subject may benefit.