PETG embed Prusaslicer
That company would have to elaborate on the process. That's not the result you typically get with consumer-grade FFF printing. Is it possibly a resin printer?
The model linked to as an example https://cults3d.com/en/3d-model/tool/embedded-albert-einstein-bust-transparent-3d-print?fbclid=IwAR00WOi3wvILhcVfxCmDn4X9gm-9B5yFh6qwGJTcWmWEfV9ggIPU1qythuU in the Facebook post suggests it's FFF 😮
That's pretty cool. There's no settings in the slicer to get that effect through, you just download and print the model. There will probably need to be some fine tuning of speed, retracting, temp, etc. to get it perfect but you should get a decent result with the default settings and go from there.
Yeah I would suggest sanding it with various sandpapers in order to achieve that result just like the video linked above.
Prusa Slicer 2.2.0...