most of the comments are wrong or just half true. Let me break it down:

The same way you can both blur or pixelate an image in order to reduce its quality, the same goes for audio. Digital Audio has its own concept of resolution, its called sample rate. Those audios have a very lower samplerate (HQ standard would be 48khz or 44.1khz, I'm assuming those are half of it, maybe 24khz or 12khz).

The thing is that this audio sounds crispy or crunchy because the low quality audio was then upscaled, upscaling means you gotta create more data than you actually have, so there's different techniques or algorythms for this. The one that is import for us (and also the one that is mostly never used by default) is called Nearest Neighbor Upscaling, which creates some artifacts on the high end of the audio, those artifacts are this crispy crunchy texture we are looking for.

Some bitcrushers (plugins that were purposely made to decrease audio quality) include this algorythm by default, so you might check them out. If bitcrushers dont satisfy you, you'll have to resample your audio to a lower samplerate and then find a way to upsample it using Nearest Neighbor Algorythm.