Combat roles in a Tactical RPG

So, my friend and I have started work on a minimalist visual novel/tactical rpg hybrid game of sorts. Our main inspirations, however, actually mostly include CRPGs such as Baldur’s Gate 3 and Dragon Age: Origins, though our combat is sort of top down and on a grid. (I promise the game is much more stripped down than the inspirations mentioned).

I was thinking about how to implement combat roles for the party as well as how to think about party composition, balancing, and making combat fun, tactical, and able to be accomplished.

My main question is, do we need roles for the different character classes such as “tank”, “healer”, “DPS”, “control”, etc. Is it necessary for all classes to fit into such roles? Can roles be combined? How does this get over designed?

I think the main thing I’m worried about is making sure to implement a good deal of power fantasy in the combat’s design, mainly in the form of the protagonist. The protagonist in question is a demigod so I was thinking they’d have their own set of classes to choose from that are similar to but not the same as the classes that the other party members will have and that the demigod will always be the DPS so that they have a good level of power fantasy.

But again it begs the question, how necessary are “combat roles” and is it too difficult to roll your own on those instead of copy pasting “the big three?”

Sorry if my thoughts are a bit jumbled or if my question isn’t clear.