Yes you can upgrade a lot of Dells, but the maximums in their manuals are based on their supported maximums, so if you run in to problems, your Dell support probably won't be of much use.
I find people trying to compare to a Dell (especially to anything which isn't trying to be a competitor - the XPS) come off a bit naive. Once you start talking about the XPS, the price difference shrinks. In the UK the latest XPS 13 with an i7, 32GB and 1TB and the better screen is around £2,000. The M2 Macbook Air 13 with 24GB and 1TB and fast charger is £1,979. The 13 pro with same specs is £2,149.
Having owned an XPS before (with its flexing chassis, coil whine, overheating, cpu throttling, noisy hot fans, smelly plastic), you couldn't pay me to have one.
Such as https://www.dell.com/en-us/shop/dell-laptops/inspiron-15-lap... which is $530 at the moment but you can get it for cheaper during Black Friday. The manual may say up to 32GB but installing 64GB works just fine, as the CPU supports up to 64GB.
For $330, you can get an i5 Lenovo IdeaPad 14" today but it goes up to 36GB only because one of the 4GB RAMs is soldered https://www.microcenter.com/product/666315/lenovo-ideapad-3-...
You can install 64GB RAM to i3 laptops as well, which can be as low as ~$300, for example https://www.dell.com/en-us/shop/dell-laptops/inspiron-15-lap... is currently $350, but you can get a similar one for ~$200 during Black Friday.
64GB RAM in a laptop may cost a fortune in Apple-land, but it's pretty cheap to get for "normal" laptops.
(You can't upgrade RAM with Acer Swift 3, it's soldered.)