what application can fill PDF forms

Strange, use here to fill in different pdf forms.

Can you ask pdf form 'maker' how to fill in that form?

See if PDF Max Pro meets your requirements and wishes.

If the app meets your requirements and wishes, the Desktop version is cheaper than the subscription.

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You can use Preview to fill in a PDF file from a macOS computer, see -> Fill out and sign a PDF form in Preview on Mac

Fill out and sign a PDF form in Preview on Mac – Apple Support (UK)

If all goes well, if you type one x, then type some more x's, then rarely 'enlarge' the input box / input field.

This of course depends on the type of PDF form you have.