I don’t have UE4 installed this time, so I can’t see the folders. It would be advisable to create a copy of the file sdkmanager.bat - just in case you screw it up.
set SDKMANAGER=%STUDIO_SDK_PATH%/path/to/sdk/sdkmanager.bat
can be changed. “call” uses the SDKMANAGER path to launch the right build tools and extras with the batch file.
set SDKMANAGER = “C:/the/location/of/the.bat”
In Android Studio, in the managing tools options, delete all the build-tools apart from 28.0.3. Everything should be installed automatically then in the command prompt.