Yeah. They all use the same text editor library.
KWrite has a very small amount of features (which is still way more than Notepad though). It still has syntax highlighting and stuff. I would recommend it if you are editing stuff like grub/sshd configuration files or reading log files.
Kate has a "Sessions" thingy, unless you are on Debian 12 or older. So when you want to open a directory as a project and save some metadata of your session, this is a good idea. Also, proper LSPs and stuff.
KDevelop is fully meant for programming, using build systems and such. It does require a fair bit of configuration on the first time though. So if you have a CMakeLists.txt in your project, you can use this thing to make your work easier. It works with other build systems too, I just didn't try them out.