Change Font size based on text value of other cell

Hello Excel gurus out there! I'm looking for a way to change the font size of a cell K3 based on the text value of cell O3. If cell O3 has the word 'Written' in it, the font size in K3 would be 22. If cell O3 has any other value, then the font size in O3 would be 12. This formula would be true for any row in the sheet (20,000 rows). Ideally it would happen automatically but running a macro that checks a selection of rows would also work.

Thank you for any help or advice on this task. I've been banging my head on it for a while now.

Cheers!

Hey Alan! Thanks for the help on this! Your solution works quite well for a single cell. Is there a way to make the font in row 'K' update when I do a bulk change in row 'O'?

Maybe some background on my usage for this will help. We're using Excel to record a voiceover script. At the start of the session, all of the lines marked as 'Written' will be at the 22 pt font. At the end of the session, I'll bulk change the status column to 'Recorded' and then all of the lines that were at the 22 pt font would return to their native 12 pt font. Right now when I go to bulk change the status field either to or from the 'Written' status, the font only updates in the cell of the first cell in the 'K' column that I clicked on. I tired to copy and paste the updated status as well as grabbing the bottom right corner of the cell and dragging downward.

Any thoughts? Really appreciate the help!