Yes, you can use TurboTax to amend a 2018 H&R Block tax return.
To use TurboTax to file an amended return originally filed using H&R Block, you would first have to recreate your original return exactly as it was filed using TurboTax before you could start the amended return. Select one of the following Turbotax online products, TurboTax 2018 Online Product Guide or if you prefer using the CD\Download, 2018 TurboTax CD/Download Product Guide.
Once you've recreated the original returns exactly as they were filed, save your return. Next, amend your returns. See How
do I amend a 2018 return in TurboTax?