Here's a fairly comprehensive list of exchanges that provide DCA. There are other ones that might have added a DCA method that I'm not aware of, however. Additions / corrections welcome!

Dollar Cost Averaging. The answer to the question “Is now a good time to buy Bitcoin?” https://cointastical.medium.com/dollar-cost-averaging-the-answer-to-the-question-is-now-a-good-time-to-buy-bitcoin-a84e518f50f0