Honestly, I've asked the same question, and while there's alot you can do to secure your online activities (using bitcoin, pgp encription, 2fa, protonmail etc..) you have virtually no control over whether the authorities take notice of your package. You're basically rolling the dice. If they do intercept your package one of two thinks will happen;
1. If they decide the amount of illegal drugs is for personal use, you'll get a pink slip saying that your package was contained contraband and was siezed by authorities. If this happens there will be no consequences (other than losing your money and the package), although you should consider the address as compromised and not place any future orders to that adress or
2. If the quantity is large enough, LE will do a kind of sting and suprise you at the doorstep when you go and get your package. This is scary, but your best bet is to feign ignorance. Denial a beautiful thing.