I made sure the first Android device I got had an SD card slot. It came with limited "internal" memory, but an SD slot seemed to offer plenty of space for expansion. Ha. As it turned out, most apps couldn't be moved to the external storage. Or keep their data there. It the end, it turned out to be nearly useless and I realized I'd been sold a pig in a poke.
About a year ago, I got low-end Motorola E4 and discovered that it supported "adoptable storage" by which the SD card was integrated into the device's filesystem. I was skeptical, having gotten burned before. But I bought a card and plugged it in. It warned me that it might be slow. But it was fine. It worked great. Seamless. I helped my son set it up on his Moto Z Play and it worked fine.
I liked the Moto E4, except for the camera. So I decided to step up and get a Moto X4. I moved my SIM card and SD card over. Except the X4 doesn't support adoptable storage. The option isn't available.
There aren't any convincing explanations for why Motorola chose to not implement adoptable storage for this model, except as a business decision to drive people to more expensive phones. Sigh... I hate that aspect of capitalism that makes companies create intentionally inferior products to maximize revenue, rather than just making products with the features that people really want.
Unfortunately, it's probably a showstopper for me: I use syncthing to manage my music, photos, and working documents and it can't write to SD cards due to the same vagaries of Android that made my first SD card so useless. So I'm planning to return the phone. What a huge disappointment.