There seems to be some confusion between Copperplate and Flexible nib handwriting.

Ordinary handwriting can sometimes be enhanced by being written with a flexible nib which creates
swelled downstrokes when a little pressure is applied. The effect can often be very attractive, but it’s
miles away from the handwriting developed from the engraved copies of the lettering produced by the
eighteenth century English writing masters.
For those who would like to handwrite in the Copperplate style but are a loss to know where to start;
this may be of some help.

“Classic” Copperplate is a disciplined hand with no room for personal expression. When properly
formed, the minuscules in particular, are virtually identical from one writer to the next and it is also
difficult to write well. All this sounds very forbidding, but the results can be exquisitely beautiful
and extremely satisfying to write, when the letters are properly executed.

For those just starting out, this routine can be invaluable. There is little here that is new - this is
just my ‘take’ on it.

All the minuscule letters are formed from the basic shapes numbered here from 1 to 7, with the exception of the letters q s x and z which require the shapes 8 to 11 in that order.

With a couple of minor modifications, all copperplate minuscule letters are formed from combinations
of these eleven shapes, as in this example -

There are one or two ‘rules’ which are easy to remember.

1) Copperplate is written at a slope of 55 degrees from the horizontal.
2) All straight lines are parallel in weight from top to bottom and all weighted strokes are as close
as possible to the same width as each other.
3) From upward hairlines, all downward swelled strokes begin just after turning at the top and
the pressure is released just before turning at the foot. This is demonstrated in the compound
curved stroke (no 4). Note that the two elements of this stroke are parallel and are the same width.

Stroke-width consistency is purely a matter of touch, which can be developed over a period of time.

‘Classic’ Copperplate is produced with moderately weighted strokes which adds to its elegant
appearance.
It is possible to write in this style with a fountain pen but the best results are achieved with a
medium-flexible dip nib in an oblique holder.
Excessively flexible nibs should be avoided as they can make consistent control difficult to achieve.
Moderately flexible nibs such as Gillott 303 are ideal for Copperplate.

There is another version of this script known as Engravers’ or Engrossers’ script which is drawn
as opposed to being handwritten.

There is, of course, a lot more to learning this script, but perhaps this may help as a start.