How do I type a schwa character - ǝ (the upside-down e) on MacOS?

I have tried following instructions that say its in the emojis and symbols but the upside down e is not in there for me.

Then there is a hot key about Option + Shift and then Option + A, that has not worked for me either.

What keys or input methods can make this easier than cut and paste?

In Emoji & Symbols, type schwa in the search box.

On the ABC Extended input source, type option shift semicolon, let go and then type e. ǝ

If you need it a lot, you can put one in your typing replacer.

System Prefs > Keyboard > Text

Add your text to type on the left, then paste a schwa into the right, then you've got one every time you need one…