You can easily merge PDF files with built-in tools right on your iPhone and iPad.
Merge PDF files not only makes it easier to share multiple documents with others, but also helps reduce the hassle of many different files. If you use an iPhone or iPad, you can rely on several available methods to merge 2 or more PDF files quickly.
Doing
We’ll use the Files app to perform the PDF merge operation. The advantage is fast and easy to use. But it’s also worth noting that it only combines files in alphabetical or numeric order, so if you want the PDFs after merging to be sorted in a specific order, you have to rename the documents in the order. before.
• Open the Files app on iPhone or iPad.

• Browse to the folder where the PDF documents need to be merged are saved.

SCREENSHOTS

• Select the PDF files to merge, if the PDF files are scattered in the Files app, use the folder-shaped Move icon to move them to the same folder. This is a must.
• Once you have made sure to select all the PDF files, click the More button at the bottom right of the screen and choose Create PDF. You should see the merged PDF file immediately in the same folder.
• The Files app will not delete the original PDF files, so you must manually delete them if you want.