It's tricky to tell from the screenshots but the first block looks like 'Wood Ramp Incline Half' which, as the name suggests, is already a half sized block (See final screenshot in this answer). I do not believe there is any smaller sized block of this type.
The second block looks like a composite of two different blocks, 'Cobblestone Quarter CNR' in front with 'Cobblestone Block' behind which has the appearance of a single block in your screenshot.
Interestingly I couldn't find the vertical cobblestone blocks in your pic without them being centred, so I recreated their look with wooden blocks painted as cobblestone. Can be a viable option if you are just doing this for aesthetics.
You may also have better luck if you use the debug tools to identify the blocks yourself. You can do this by:
- Launching your world with Cheats Enabled (i.e. creative mode)
- Press F1 to open the console and type dm to enable Debug Mode
- Press F3 to display the block dialog
- Place the crosshair on the block of interest and watch for the name and details to appear in the dialog
- Press TAB and select the Creative Menu then type the block name into the Search Box.
Some blocks are only available in Creative but their description will tell you if this is the case.