Acrobat Reader for iOS is a PDF viewer. It offers the basic functionality (such as viewing PDF documents, adding comments including a handwritten signature, filling out forms, searching, printing, etc.) for free. However, it does not convert a Word doc to a PDF document.
If you subscribe to the Adobe PDF Pack online service, you can open a Word (Excel, PowerPoint, JPEG, PNG etc.) document and convert it to PDF. Additionally, you can covert a PDF document to other formats as well.
You can use the Adobe PDF Pack online service from mobile devices and desktop/notebook computers.
Hope this helps.
Microsoft Word on iOS can export (share) to PDF with a subcription then get Adobe Fill & Sign from the App Store. I didn't see a way to provide security/encryption to final PDF or the app itself. Plus on the ipad pro it looks awful. Hope you will update soon.