This is highly dependent on the baseboard material. With enough pressure and time almost all baseboards would conform to the wall but let's be reasonable.
If you just want to get done with it and it look OK, then go MDF baseboards. Yea I would never install them but they would do exactly what you want. However you will need to put some moisture or weights on them if the wall is really bowing, in or out. And when I say weights I used 25-45 pound olympic weights at sites for this exact thing.
Going to something like pine or oak, they still bend. It just takes more moisture and pressure. I had a curved wall in the last bathroom I did in a basement. Dipped the pine (just factory primed) boards in water, then pushed them in place with plates. I had to do a lot of wetting and used almost 300 pounds in weights for the wall.
So weight is one thing. You can use various things (not just real weights) but it depends on how bad the wall is. But you do want a lot of pressure because if you put a couple of 20lb weights on a long board, it will probably push out a 1/4" on the wall and you start over then.
Also the silicone is a good idea. Do not use liquid nails or similar as it is a PITA to deal with if the board pops out even a fraction. The liquid nails type of adhesive seems to dry "bigger" and can also create issues. Silicone cleans up easier (scrapes off with putty knife) so go that way.
Depending on the type of wood if your walls are close to flat you should be OK. Note that if there are variations more silicone is needed there to help during the first few weeks. The wood will conform to the wall eventually. I would suggest that each piece has pressure for a full day meaning you may have to do sections if you don't have enough weights.