Only able to print on legal size

Hello StephanieBarbara22,

Welcome to Apple Support Communities. 

We understand that you want to change the paper size when printing. We are happy to help.

Please use the steps here to change the paper size when printing from your iPhone: Use AirPrint to print from your iPhone or iPad - Apple Support

"Print with AirPrint

1. Open the app that you want to print from.
2. To find the print option, tap the app’s Share button  or  or the Actions button.
3. Scroll down and tap the Print button  or Print. If you can’t find the print option, check the app’s User Guide or Help section. Not all apps support AirPrint.
4. Tap No Printer Selected and choose an AirPrint-enabled printer.
5. Choose the number of copies or other options, like which pages you want to print.
6. Tap Print in the upper-right corner."

When using a Mac, please use the steps here to change the paper size when printing: Choose a paper size for your printed document on Mac - Apple Support

"Change paper size for printing

You can specify the paper size that you use in your printer.

1. With a document open on your Mac, choose File > Print.
2. Choose a paper size from the Paper Size pop-up menu.

In apps such as Pages or Microsoft Word, you can also specify a page size for a document as you’re working on it. When you print, the document is already formatted to fit the paper size you selected. However, you can choose to scale the document to fit your printer’s paper. See Reduce or enlarge pages and images to fit on a page.

In most apps, the Paper Size menu has a Manage Custom Sizes option. If you choose this option, see Print on unusual sized paper by creating a custom paper size."

These steps may be helpful. Let us know if you have further questions.

Take care.