PhotriusPyrelus

The first one looks like glass panes (https://wiki.vintagestory.at/index.php/Glass#Leaded_glass_pane).

The second looks like it's just chiseled out of two blocks.  Unless you're talking about the glass in the bottom right, and I have no idea how you get vertical slabs like that.

EDIT:  Derpy doo.  I didn't read.

Wall-carvings.  You use a chisel.  Place a block, equip a chisel to the hot bar, select it, right click the block.  You can now remove mini-blocks (1/512th) from the block.  You can press F to change the size of the amount removed or added, you can also add additional blocks by drag and dropping onto the big +.  I'm not sure what the limit in number of blocks is.

EDIT2:
Some demonstration screen shots:



Alternating base block colours in the last one just so you can see the number and positions of the base blocks.