Thank you for such a prompt reply. The answer to your question "Were you thinking about this scaled parenthetical example as performed in Pages v14.3 on Sequoia v15.3.1?" is a definite "Yes!"
I copied and pasted the code (correct term?) into the Equation Editor in Pages and of course it worked beautifully. I am just not at all familiar with any of that code, the indented structure & commands. Steep learning curve ahead?
The link you provided 'About LaTex etc.' has as an example:
\left \{ 6 \tfrac{4}{5}, \, \sqrt{49}, \, 6.\overline{3},
\, 7\sqrt{5} \right \}
I am familiar with this entire sequence, and have used the \left & \right commands to produce required results. This scales the braces to accommodate increased height required . I just haven't found anything similar to scale parentheses.
I'll practise with your kindly provided example until I make some understanding of it.