Change a cell's font size

Ctrl+Shift+Period grows the font, Ctrl+Shift+Comma shrinks it (or use the toolbar stepper).

What it does

Select cells and press Ctrl+Shift+Period to grow the font one step, or Ctrl+Shift+Comma to shrink it — or use the [−] size [+] stepper in the toolbar. Font size is presentation, separate from the cell's value: resizing =A1+B1 styles the number without touching the formula. It undoes and redoes like any other edit, and stays within a sensible [6, 96] range.

Verified behavior

Matches Google Sheets: Font size is a per-cell presentation attribute, independent of the cell's value or formula, that undoes/redoes like any edit. Increasing bumps the size up one step and decreasing bumps it down one step, off the cell's current size. In the Google editors the keyboard shortcut to grow the font is Ctrl+Shift+Period and to shrink it is Ctrl+Shift+Comma. Studio's unformatted default is 10px (matching Google Sheets), so a single increase yields 11 and a single decrease yields 9; sizes are clamped to a sensible [6, 96] range.

Ctrl+Shift+Period grows the font one step

Given

A1 = x

When I click A1, then press Control+Shift+Period

Then

A1 is fontSize=11

Ctrl+Shift+Comma shrinks the font one step