How to specify scale option in wavelet transform?

I want to obtain wavelet coefficients for the signal shown below for various scale values.

The 'cwt' or 'dwt' matlab command doesn't provide an option to specify scale during input.I want to plot the wavelet coefficients using 'sym4' wavelet for various scale values such as 16,32, 64 and 100 and would like to see a plot as shown below.

I'm conducting this experiment to see if the following theory is correct: an analysed process contains signals with duration "a", then the wavelet coefficient at the scale "a" has the largest amplitude.

The signal shown above has a duration of 32 seconds. If the above theory is correct then the wavelet coefficient with a scale of 32 should have the largest amplitude compared to other scales.