I cannot change ringtones for different contacts. There is no option in any menu to do it. My S7 was perfect, I could do everything. of course, I had that rooted.
But I have had nothing but trouble with this S20 since I bought it 2 months ago.
Open contacts then select a contact and tap on edit. scroll to bottom select view more. scroll to bottom and you should see ringtone. If you have not selected it before it may say something like access storage and then you can select a ringtone for the contact.
