Buying BTC through using
dca is good and more convenient for investors, it aids an investor to control the volatility of BTC, and in my humble opinion it prevents naive investors from investing more than they can afford to lose in one lump sum purchase. Read more about dca in the link above.
Since the dollar-cost averaging strategy's main domain is an automated purchase. Does it mean that I'm required to leave some funds active to enable the automated action take place. Or I can also carry on the strategy manually; having a particular date I come for purchase irrespective of the price?
Manually is best and safest, exposing your funds to exchange vulnerability and out of your custody for asnlittle time as possible.
It does not even have to be fixed amount or time. For me every 2 weeks is really good. Or a scheduled amount (every time you save 100$ for example).
You also save on fees for exchanges with less frequency but obviously the more frequent, the better your averaging.
Also explore p2p platforms like bisq. Safer, once you get the hang of it.