power supply - Limiting macbook (usb c) charge level to 60%, during prolonged desk usage, by plugging into a smaller charger

Having scouerd the internet, I gather keeping a lithium battery at 100% charge for prolonged periods is a bad idea.
While there seems to be a workaround for magsafe macs (How do I keep a MacBook battery charged to only 70%?), there doesn't seem to be a straightforward approach for the usb c version.
When plugged into a 15 watt usb c phone charger, the mac indicates power source - AC, battery not charging.
Is powering this way a good idea? Could it limit battery cycles and potentially prolong it's life?