On youtube is a video of an SVA accepted portfolio for graphic design. Just type in SVA accepted portfolios (SVA Accepted!). It’s 19 min long. I didn’t watch it but it may be helpful to you. (lots of others also but that one was for graphic design)
National Portfolio Day is 100% on line this year. Get on their website and check the dates. NPD is where different schools will evaluate your portfolio and give instant feedback as to what to focus on (for admittance to that school). It is very valuable. Get on their site and sign up immediately. I think the sign up started Aug and first session (not sure where) starts Sept 19. (pre-covid you needed to show up very early and go jump in a long line to talk to people–which was fun because you could see what other students have in their portfolios).
My D went to Ringling and back then the website said for the application to draw a corner of your room as a way to show your drawing skills. It wasn’t necessary to be a fabulous artist to get in but all drawing submissions needed to be “drawn from life” and absolutely nothing from photographs.
My D went into animation and at portfolio time they looked specifically for quick sketch and action art. No insight into graphic art unfortunately.
Do NOT get discouraged by portfolios of some of the art you may see from “accepted portfolio” on the internet. You already know those students have art training and are “showing off” a bit. Lots of people with no formal training are accepted. The schools look for “potential”. This is also where “good grades” can help–the good student is someone who can learn and take instruction usually.
My usual advice though is to look closely at student work posted by the college and see if you like the style and product that is coming out of the school.