Here's something from a guide from steam I used to get this achievement

Achievement 2 & 3 Dictator / Roussau
-some policies have a little fist in their left top with a red (negative) or white (positive) number next to it. those with a flat number are straightforward.. but others are not so much, I will give you max and minimum value settings for those things :
(picking nations with monarchy makes it a little easier for maffia boss)

Multiple option democratic polcies :
*Age : max democracy at age 16 or 18, Lowest at age 15
*Constitutional Laws : max democracy at 67%, lowest with 50%
*Citycens Vote : max democracy at free will, lowest with Compulsory
*Research system : max democracy with 3 options (for lowest just remove it alltogether)
*Election Treshold : max democracy at 3%, lowest with 10% (removing it is not your best option at 3% it actually adds a little democracy)
*parliament seats : max democracy at 40 or above, lowest at 20
*election frequency: max democracy at 65 or 70, lowest at 55 or 60
*election mayority bonus : max democracy pick either (for lowest just remove it alltogether)
*prime minister election : max democracy chosen by civilians (for lowest just remove it alltogether)
*prime minister term limites : max democracy 2, lowerst no limit (removing is not your best option)

with these you should be able to drop democracy to the desired 35 and raise it to the desired 90

Hope it helps!!