This website purports to show 2025 fares:
https://istanbul.tips/istanbul-public-transportation-fares/
As you can see, the situation is quite complex. The best I can tell, a single Metro/tram/bus ride costs just TL 20 if you have an Istanbulkart (but you must pay TL 130 for the card; it used to come loaded with enough money to cover one ride, but I see no indication that is still the case). The cost per ride can ascend to TL 70 for a single-ride ticket, but there is at least one option between those two extremes. I'm not going to pretend I understand what's going on. Things have changed quite a bit since I visited Istanbul in the fall of 2023. I wasn't aware of tokens in 2023.
Someone posted on this forum a while back that you can pay for at least some transit with tappable credit card. I don't remember whether the comment was about the Metro, the tram, or buses. The article I've linked doesn't seem to mention that option.
The current exchange rate is 35.40 Turkish lira to $1, so the single-ticket option costs about $2 per ride, whereas using an Istanbulkart reduces the cost to less than $0.60. It doesn't sounds as if you'll be using transit frequently enough to worry about the difference. I can tell you I had a frustrating time loading additional money on my Istanbulkart. Others haven't struggled as much as I did.