Trading in for an upgrade

So I currently have a MacBook Air 2015 (I want to say 13”) and an iPad 7 generation with Apple Pencil, I’d be looking to upgrade to take away having 2 devices and merging them into one with either the iPad Air or Pro, yet to decide.

I have a large desktop now with work so doing any essays and such can be done on there, eliminating the pro I had for keeping my laptop and I use my iPad for note taking and such for uni so hoping that I could upgrade to a more larger/newer model.

Now my question is after that context, what is the best way to do this? I’m a student so would like to use that discount to my advantage. When looking online it only seems to offer me the chance to input info for one device, is it better for me to go into store and do this? Is that even possible? Or am I better to go somewhere like CEX (off the top of my head example) and cash both devices in there and then put the funds towards the new device.

It may be a unique situation so appreciate if no advice can be given but open to any and all suggestions.

Thanks.