My question is I have ijoy capo 100 and I was wondering if i could use a RDTA/RDA build on it
You absolutely could use either, but be aware of the difference between an RTA and an RDTA. An RTA is like a tank that you currently use, but uses rebuildable coils and replaceable wicks. An RDTA is like a dripping atomizer with a reservoir of liquid instead of a shallow-ish well. It too has a rebuildable coil system and replaceable wicks, but differs in where the liquid resides relative to the coil. There are people who swear by both; I prefer RTA's.
It would be best to start simple. Single-coil RDA's like the Serpent Mini and OBS Engine Nano are easy to learn with and cause few headaches. Don't go after difficult decks (like I did). Postless decks for example. You'll spend too much time fiddlin' and cussin' (like I did) and less time vaping. Those types of atomizers can take monster-sized exotic coils that, IMO, only waste juice, battery charge and time.
When you choose a tank, since your mod's maximum wattage is 100, you may want to look at building something of medium resistance (say 0.4--0.6) at first to see how your battery life holds up. The higher the resistance coil, the less wattage it is going to need, so you'll be able to balance your desire for clouds/wattage with battery life.
Not calling you out Anna, but this is not necessarily true. The wattage required to get a build up to a temperature that produces a desirable vape is mostly governed by the size and surface area of the coil(s) used. A big coil or big pair (or trio, or...) needs more power regardless of its resistance.
For example, my Goblin 1.2 has two 0.40 Ohm coils for a total build resistance of about 0.22. My Moonshot has two 1.0 Ohm coils for a total of 0.50-ish. The Moonshot is best at about 55 Watts while the Goblin nearly burns up over 40. The reason is that there is more wire and larger diameter coils in the Moonshot build. Both are fantastic vapes, but I use the Goblin on a single cell device while the Moonshot really needs a dual cell device.
The Moonshot is one of those "challenging" devices to build with because it's really designed for cloud chasing and can handle big, fat exotic coils. Buying it was a mistake because I was just starting out back then. But it was on clearance and the Youtube reviews made it look
soooo easy, dude!