If it’s not in your physical possession, it’s not your computer. If it’s not your computer, then whoever administers the computer, or whoever [points a gun at/gives enough money to] the administrator of that system can access whatever you put on that system.
If a “cloud” or “service” is involved, then you can trivially use them to move or store data that you encrypted locally on your computer with your key that was generated and stored locally and never left your system. But subject to the limits above, the administrators of the other computers will still be able to see metadata like where the data came from and is going to. And they might be able to see your data too if you ever (even once, ask Ross Ulbrecht) failed to follow the basic encryption guidelines above.
You can make metadata access harder via VPNs and Tor, but you CANNOT make it impossible- in the worst case, maybe your adversary is controlling all the Tor nodes and has compromised the software.
Which leads me to my last point, if you did not write (or at least read) the code that you’re using to do all of the above, then you’re at the mercy of whoever wrote it.
And, if you try to follow perfect operational security, you will have a stressful and unpleasant life, as it’s really really hard.