Frankly I think you can't predict it. I am fairly sure one of my siblings would say they didn't like being part of a large family - but the rest of us (obviously I can't be sure about anyone's opinion but mine!) liked it.
I LOVE Christmas and big family gatherings. But if you lived close to family and your DC had cousins of a similar age, that can be recreated. Equally we were a large family of introverts - so alone/quiet time was always valued and understood despite there being a lot of us.
I am the youngest and I do think it's a pertinent point that it's easier to be the youngest/a younger one - I did struggle growing up with the fact that any sports club I joined already knew one of my siblings, I was always welcomed as 'ah, the youngest [surname]!' by people (kindly) and my siblings seemed to have just done everything before me. Particularly as a teen I was very impatient to learn to drive/be allowed more freedom/move out etc.
But I had parents who on the whole were excellent - they encouraged (and continue to encourage, even though we're all adults now!) valuing yourself and your achievements in a non-comparing manner, supportive behaviours between us as siblings, etc. We got enough one on one time although more with Mum as younger kids as she was at home whilst Dad worked.
I think age gap wise, larger age gaps can often help to be less competitive, but I didn't feel particularly close to some of my older siblings as a child. Smaller age gaps can mean more competitiveness, but can also mean they're closer - I get on very well with most of my siblings but being the youngest I'm at quite a different place in my life to them.
You cannot plan future relationships between people, I'm afraid. Particularly when you have no idea what personality a future child might have. That's just the way of it!
I would like 3 children - maybe 4. Definitely not been put off!