From within the Editor you can go Edit → Project Settings, search up Trace Channels and click New Trace Channel… (and set to Ignore by default)
Once you add it there, it will be present in your ProjectFolder/Config/DefaultEngine.ini as one of the ECC_GameTraceChannels in this kind of format:
+DefaultChannelResponses=(Channel=ECC_GameTraceChannel1,DefaultResponse=ECR_Block,bTraceType=False,bStaticObject=False,Name="Projectile")
Then just replace your ECC_GameTraceChannel1 in your example with the corresponding number and change the collision profile of the component of your choice to start overlapping or blocking the new trace channel you created.