The accepted answer for the question How do I convert a Word document into an ebook? describes how to convert a book in
.docx format to AZW3.
As is very clear from the 3rd picture in that answer, where AZW3 is selected as output format, that there is a whole list of "calibre output formats". Searching the latter phrase should get you to the complete list of supported formats in the FAQ:
AZW3, EPUB, FB2, OEB, LIT, LRF, MOBI, HTMLZ, PDB, PML, RB, PDF, RTF, SNB, TCR, TXT, TXTZ.
From that list, someone can just select what they prefer for their device and/or software¹. For iPad users that depends on their software, but if that doesn't support AZW3 directly, it probably does support EPUB.
Assuming you already can convert the
.docx to AZW3, and since the capabilities of EPUB and AZW3 in formatting the eBook are very similar, selecting the conversion is the only thing you (or the owner of the iPad) needs to do. There is not going to be any additional considerations, beyond what you do for going from
.docx to AZW3, on how to go about the conversion².
¹ One can argue that if the device/software does not support any of these formats, it should not be called an eBook reader.
² That should only be an a concern if the other output format allows for very little formatting control, like TXT