HOW TO PUT THE AMOUNT IN LETTERS ON THE COVER PAGE OF AN ANNEX IN THE CONTRACT

Inside the contract we want to add the amount in words.
This is due to the client's operations that we already have, what happens is that the contract has an annex which is the cover page, inside the cover page there is a section where you need to have the amount of the contract that is put in the lines section so that you can see the preview of the contract. So our question is:

Is there any way to put code in the variable that is inserted in the cover page so that it gives us the amount in words? In RTF it does not allow it, so how would it be possible through XML?