I'm curious to know what is the best way to coinjoin my dollar cost averaging UTXOs? I have about 0.15BTC now in UTXOs after a few years of averaging. But they are all from Coinbase. They are of varying sizes. What is the most private way to coinjoin them? Do I send them all at once to Wasabi wallet? Then transfer it to cold storage from there?
Coinbase already knows how much BTC you have and which addresses those coins are in, so if you send all your coins at once, no new information is revealed to them. If you wanted to add privacy from the perspective of others watching the blockchain besides Coinbase, you could gradually send your UTXOs one at a time and do 1-2 coinjoin rounds in between deposits.
And what if I only want UTXOs that are larger than 0.02 in my cold storage?
You can send specific sized amounts using the RPC interface -
https://docs.wasabiwallet.io/using-wasabi/RPC.html#payincoinjoin