[JustOneMore20]

There are several carpet/ground covers being used in those layouts. Some common ones are Glosso, Dwarf Hairgrass, Riccia, and HC.

Almost all ground cover plants require atleast moderate lighting, most require high lighting and co2 injection, as well as a fertilization routine.

Marsilea minuta looks much like Glosso, but grows much slower and would work in medium-ish light.

I can't tell exactly what is used in the first....I see some Glosso there and maybe Dwarf Hairgrass.