I have a late 2016 macbook with a charger that fails often. I bought one that I thought would work but am afraid to try it until I know for sure.They are both c chargers, but the original one is 29W and the new one is 61w. I think that using one with higher wattage is ok, am I right?
Power adapters for Mac notebooks are available in 29W, 30W, 45W, 60W, 61W, 85W, 87W, and 96W varieties. You should use the appropriate wattage power adapter for your Mac notebook. You can use a compatible higher wattage power adapter without issue, but it won't make your computer charge faster or operate differently.
Make sure you're using the correct USB-C charge cable
For the best charging experience, you should use the USB-C charge cable that comes with your Mac notebook. If you use a higher wattage USB-C cable, your Mac will still charge normally. USB-C cables rated for 29W or 30W will work with any USB-C power adapter, but won't provide enough power when connected to a power adapter that is more than 61W, such as the 96W USB-C Power Adapter.