Especially in TiTs where the writers can even remotely justify it
TITS is a bit different in that the setting just let's you science stuff away and Steele can reach a point where they might as well be made out of silly putty. Which is just as well given how ridiculous some characters can get.
Admittedly Shizuya is a bit in the minority. There aren't
that many characters or encounters waltzing about with gigantic earth-shattering rods. Even then, using this NPC as an example, you needed the necessary capacity for several of her scenes to even enable the option.
Player side, a large amount of NPC's with huge rods worked that way. If you didn't have the capacity, you couldn't possibly take them.
They handled the NPC size limits with a bit of the same rules. This is mostly due to NPC's
also having capacity limits and some have alternative scenes for being too big/too small. A regular unmodded human is barely going above 7-9 inches comfortably but a leithan can take 3 times that.
It's a bit different here, instead of having to TF to be able to take the hyper futas, you just take gigantic sizes without much issue. There's a scene where you can take the Jotun no problem and I don't think you need anything special for that. It just happens.
To be fair, at least there's a not small amount of NPC's who take the players size past a certain limit into consideration.
e.g; Lyric does have capacity limits before the text outright states you're not fitting anything else inside.
Also I'm feeling a bit of what they used to call "trolls remorse" so I'm going to revisit this
and be a bit more serious.