Depends on the company. Larger consulting firms will have different levels of consultants--associate consultant, consultant, senior, manager, and principal--and will pair newer consultants with more experienced ones. You should ask the company.
This x100. Every consulting organization is different. I worked for the consulting arm (paid services) of a product company. We had levels from associate to principal and none of it actually meant anything apart from pay grade. When I joined they said "We will train you to become an expert, promote you during your career, etc." In reality the training was very basic and your level was determined by your previous job and negotiation during hiring, not by your performance. The only way to get promoted was to threaten to quit. The end result was that there were principal consultants who were useless and associate consultants who were amazing. The job title was not an indication of competence at all.
How much knowledge you need is also going to vary greatly. Some consulting firms are looking for experts because they provide a high level of expertise to their customer and they charge their clients accordingly. Some firms just want bodies to fill seats at big companies and the work may be incredibly boring.
I did consulting early in my career and I got a lot of it. Not because of the company I worked for supported me, but because I was enthusiastic and got exposure to a lot of different clients and business problems. Some were amazing, some were awful, and most were mundane. But I learned a lot. Even with the awful clients, I learned to recognize early-on when projects were going to fail and how to handle people who act like terrible human beings.
Since the demand exceeds the supply by far, most consultancies take on less experienced candidates, then train them and/or pair them with a more experienced colleague.
I've worked for several smaller consultancies focusing on different domains and technology stacks and always learned it on the job.