The clutch on my bike has been feeling rather tight. I did some searches for mechanic tutorials and found one that suggested loosening a nut near the handle bars. That did work for a bit but seems to tighten up after a while.
Can someone help me with some keywords to help my search for tutorials and better diagnose issues?
Two things come to mind as long as you aren't noticing any issues with shift into gears.
Your cable could be binding up and needs to be lubricated. They make lube for motorcycle cables that don't attract dirt that work pretty well.
Cable has worn out from lack of lubrication. If lubricating either doesn't help at all, or only helps for a few days, you may need to replace the cable with a new one.
If you suspect needing a replacement, I strongly, strongly urge you to stick with OEM, as you'll find Amazon's supply of GFKLNKL cables to be shit quality that ships to your house for free.
You'll find this out in middle of a ride with friends, or commuting to work.
The cables I know have self lubricating sleeves. If you lubricate these they often don’t last very long. But I don’t have experiences with the kind of lubricant you mentioned.
Since the cable is the most likely source I’d change the cable.