My child is new to the school, and is having a hard time managing all the work and assignments. Wondering if other families are also overwhelmed or if this experience is just unique to him. He still keeps in touch with friends from his middle school a d they have significantly less HW and just work in general...

My dd is a 7th grader at Hunter. Lots of work but not hard. I think organization is key. She is very organized and has been since birth and I think that helps her a lot.
Don't worry. They don't expect perfection in 7th grade. They know it's a year of adjustment for many kids - not everyone is coming from Anderson or NEST. You'll see that the teachers are pretty gentle with grading this year. It gets really hard in 9th grade, but that's not different from any other top NYC school.
My experience is ~25 years old, but I went to Hunter and had the same experience in 7th grade. I don't know what your DC's elementary/6th grade environment was like, but I had never really had to work hard before. It took a couple Ds my first year but I got the message. Agree that those time management skills are the most important thing to get down this year, even if the grades don't pick up until later.
No personal experience, but wanted to share that the friends I have in the HS have uniformly said it is really, REALLY hard -- a lot of work and a lot to manage. Serious executive functioning required to keep it all together. No advice, just wanted to share that what I have heard from friends is completely consistent with what you're describing. I guess I do have one bit of advice: it's a great time to help with time management and organization skills, which will help dc now and going forward.