I found this information about that plate you can read it here:
This ceramic plate is one of the Iranian examples left from the Samanid rule on the east of the Iranian plateau. During this period, many ceramic vessels were made to imitate native metal specimens, especially silver artifacts left...
Here some beautiful Thuluth letters for famous calligraphers, you will notice how accurate the writing and how calm and deliberate the calligrapher adhered to. Please study these models very well, as they are considered the finest Thuluth writings.
You are right, Reqaa Script is an easy one I recommend student to start with it, but regarding Naskh, it depends on curve strokes, that's why we call it the round script. Naskh takes much more learning time than Reqaa.