Dell Inspiron 15 3520 Intel Core I5-1235u

It should -- dual channel memory is required, but 16G in that system should be running in dual channel mode.

@ejn63​

Exactly, but what happens is that I'm going to buy a laptop and I got this 
Dell Inspiron 15 3520 Intel Core I5-1235u 16GB DDR4 512GB SSD, but I would 
like to know if this one will have Intel Iris Xe Graphics

If you have a single 16 G module or two matched (identical) 8G modules, yes the Iris XE will be enabled.  That should be the case if you're buying new from Dell.

If you're buying used or from a third party, make that a condition of sale.

I need to buy a laptop, but I don't edit videos, just music and photos, but very casually. I do watch videos. The question is, should I buy a laptop with Intel Iris Xe or Intel UHD graphics?

What do you recommend?

Either will work, but I would avoid low-end consumer-grade notebooks of all types -- that goes equally for Inspiron/Vostro, HP Pavilion, Lenovo IdeaPad, etc.

Look at a Latitude, Probook, Thinkpad, etc.  No, they won't come in for a few hundred dollars, but given the generally cheap build of all consumer-grade notebooks now, you'll be replacing those twice or more as often as a business-grade notebook.