It’s Ctrl-plus using the plus key on the numeric pad, not the one that’s shift-equals. So it’s kinda hard to do on a laptop.
From the menu it’s Page >> Text size >> choice . It doesn’t work on all sites & pages. For example, it doesn’t work on the SDMB.
In the perpetual war between whether the website designer or the browser operator gets the last word on how a page looks, IE split the difference. A well-behaved website will be set up so the browser controls are effective. A lazily-designed website will lock those controls out.