Can I make my lock screen look like this or similar?
You can set it to show the clock always/when unlocking/never, you can set media controls, wallpaper type, and that’s mostly it.
For most of us, that’s more than enough already - if you need to go into heavy ricing then you need to get into the weeds and work it out for yourself really.
It’s a lock screen - that only appears to show that it’s locked when we’re not using the computer.
Unfortunately you can’t really get that layout with Plasma 6, afaik older versions were less strict on that but also less secure. The layout will always be the same but the button styles and the text are based on your current theme. You can also change the wallpaper. Unless you’re talking about the SDDM screen?
See, older plasma versions offered direct QML modding: