I used to use TMP exclusively, which requires the use of an offline wallet, like Bitcoin Core. Now I use Evo and I still send all my bitcoin from Coinbase to my wallet, and then to Evo. Is this essentially self-tumbling? Or at least providing an extra layer of OPSEC?
No self-tumbling is not possible, if it was it wouldn't they wouldn't charge a fee. Also an offline wallet is not safer, it might be safer in terms of "I need to store my coins for a long time" but not in a not getting caught way.