Could I make the LaTeX input box larger?

Could I make the LaTex input box larger?
It is too small to input complex syntax now, not easy to write and read the content.

Automatic resizing of input fields to reflect the content is hard: Auto-Growing Inputs & Textareas | CSS-Tricks

You can set it to a fixed size though with Custom CSS (adjust width and the first height to your liking):

.rich-text-editor__popup-text-editor-latex {
  width: 600px;
  height: 400px;
  position: relative;

.rich-text-editor__popup-text-editor__input__latex {
  box-sizing: border-box;
  height: 100%;

Useful shortcut: In that larger Latex Editor break lines with Shift + Enter.

ATM the positioning of the Latex Editor popup is not fine tuned for larger, multi-line formulas, so also add this CSS:

.latex-node__tex--focused-inline, .katex, .katex-html {
  display: inline-block;

It works well. Thanks.

I find this annoying too. As a workaround, you can write out the entire LaTeX expression as regular text and then render it by highlighting it and pressing $.

I will try that.
In fact, I am a newbie to LaTex.