For me personally, I have one USB in my house, one hidden in my car, one hidden in my parent's house, and one in a small safe in our family business. That's most of my savings I made from 2015 - 2019 in there. I checked today, and I used to check the address everyday to see if they're still all there, and they're always there, thank God. Hahaha.
Softcopy is made as a kind of offline storage diversification on the USB that you are using. Having a copy is also very important, but offline security is my priority. make sure only you can access and open it. USB also has a feature to lock so that there will be a password that must be entered to open it. As much as possible, do not connect USB softcopy containing important data to the internet, to prevent viruses or malware from attacking.
and for the safebox rented by the Op it might be too expensive if there is another increase. I've never made storage in a bank safebox and of course the rent is expensive. I prefer to save with a personal safebox that I can make myself.