That is correct and how I also approach input gain. Leave the resistance to the interface. Most interfaces have attenuation switches or knobs designed for just this purpose. Even if you have a digital or analog processor between your instrument and interface, the interface should be the desired means of input control. Yes, it can be done from the instrument but as previously mentioned, in the case of a guitar or bass, the tone will change to the thinner side which is ok if that’s what you’re looking for. But if you’re looking for your tone to be fat, you will lose.
Even when an interface has a built in preamp, I would always suggest a direct box or processor with a built in preamp if you are plugging in directly. If you’re mic’ing an amp, I would approach the same way providing you’re not overdriving the mic transducer.