I'd need more details for why you don't want the position to be "sharp". For example... do you not want it be sharp on the opponent either, because you aren't a very tactical player or you don't feel tactics are reliable? Do you not want to have to memorize too much theory?
There are different kinds of tactical lines - some tactical lines are forcing and very theoretical... in other positions the entire board is involved and play is positional with myriads of tactics underlying things. Players don't play these positions perfectly.
e4/e5 on the whole requires alot of sharp memorization. And c6... I never recommend c6, tbh. It's not just the exchange that gives it problems. And if you want to avoid your king in chaos... I wouldn't recommend c6.
French and sicilian are the two best bets IMO.
You can play the sicilian in alot of different ways... they aren't all highly theoretical. There are 13 different viable main line sicilians, each with different characteristics. It's positional, but it can break down into tactics...
If you want my opinion on the different sicilians... instead of me repeating that all here I'd just recommend you read this blog post I wrote on it - A Tour of the Sicilian - Choosing a Variation as Black - Chess.com
The french, on the other hand, is a very boring opening. But it's also very hard for white to do anything interesting.
You're not gonna find an opening that checks all the boxes and yet doesn't require any real studying or effort. But from the sounds of it I'd say the french probably comes closest to what you are asking for. Usually the french is just going to be a very typical, boring game.
Against the advanced... well you might just have to learn some theory, I'm sorry but that's chess, I don't know what else you want unless you can give more details.
I've been thinking about this for a good while now. I'm looking for a calm/quiet opening after 1.e4. Although I know no opening guarantees this goal, but I'm looking for a line where trying to chaotize the position is bad, as I surmise that I have enough calculation skills to refute those weak moves. Here are some thoughts/experiences I've had:
1) The Caro Kann: It's been one my main openings for a long time, but this line has been bothering me where white makes it impossible to develop the light squared bishop without a major concession.
2) The French Defense: I'm experimenting with the French defense right now, as I think it's difficult for white to force any static weaknesses for black. But I've been struggling with the advance where it feels like white gets the easier piece play and black has to deal with his bad bishop. If anyone knows a strategically easy line to play for black here, please let me know.