Function Module : CONVERT_ABAPSPOOLJOB_2_PDF

Include : THSTXWFPL
*-------------  for modify font size
decrease fontsze foncharacter will increase
fontsize = 120.    <-- Change
fontsize = 100.  or fontsize = 80

Depend on your logon lang. My case logon 'TH' or 2.  I modified font ZCORDIA (refer CordiaNEW thai font)
*-----------------
if is_cascading is initial.
  case language.
  when '0'. "Serbian
    font = 'COURCYR'.  devtype = 'SAPWIN'.
  when '1'. "simpl.Chinese
    font = 'CNHEI'.    devtype = 'CNSAPWIN'. cjklang = 'X'.
  when '2'. "Thai
*   font = 'THDRAFT'.  devtype = 'THPDF'.
   font = 'ZCORDIA'.  devtype = 'ZMTHSWNU'.
*     font = 'THANGSAN'.  devtype = 'ZPDFUC'.
  when '3'. "Korean
    font = 'KPSAMMUL'. devtype = 'KPSAPWIN'. cjklang = 'X'.
  when '4'. "Romanian
    font = 'COURIER'.  devtype = 'I2SWIN'.
  when '5'. "Slovenian
    font = 'COURIER'.  devtype = 'I2SWIN'.
  when '6'. "Croatian
    font = 'COURIER'.  devtype = 'I2SWIN'.
  when '8'. "Ukranian
    font = 'COURCYR'.  devtype = 'SAPWIN'.
*-------------------

If you want to convert spool to PDF (ABAP List) and modify font size. I suggest you looking for FM: CONVERT_ABAPSPOOLJOB_2_PDF and mofdify form pdfcnv_convertlist in "LSTXWFPL" or "LSTXWFPD" for OTF to PDF.

Page format type "ANY" (X_65_80,X65_255, etc..) will be convert to size A4 width (8.27") x LETTER height (11"). You can change page format via

1. Change page format out (Calculate size by TWIP)
* for pageformat ANY, use A4 width, LETTER height
if pdfcnv_listinfo-orient = 'L'.
* pageformat ANY, use A4 8.27" width
pdfcnv_listinfo-pageh_tw = 11906.
* pageformat ANY, LETTER 11" height
* pdfcnv_listinfo-pagew_tw = 15817.
* pageformat ANY, LETTER 14" height
pdfcnv_listinfo-pagew_tw = 20160.
else.
* pdfcnv_listinfo-pageh_tw = 15817.
pdfcnv_listinfo-pagew_tw = 20160.
pdfcnv_listinfo-pagew_tw = 11906.
endif.

and

if pdfcnv_listinfo-pageformat = pageformat_any.
* for pageformat ANY, use A4 width, LETTER height
if pdfcnv_listinfo-orient = 'L'.
* pageformat ANY, use A4 8.27" width
pdfcnv_listinfo-pageh_tw = 11906.
* pageformat ANY, LETTER 11" height
* pdfcnv_listinfo-pagew_tw = 15817.
* pageformat ANY, LETTER 14" height
pdfcnv_listinfo-pagew_tw = 20160.
else.
* pdfcnv_listinfo-pageh_tw = 15817.
pdfcnv_listinfo-pagew_tw = 20160.
pdfcnv_listinfo-pagew_tw = 11906.
endif.
endif.

2. Seek keyword fontsize=120 and reduce it to < 100
3. change calculate fnt size
*fontsize = ( charwidth_tw * 120 ) div fontcharw_tw.
fontsize = ( charwidth_tw * 100 ) div fontcharw_tw.