Yeah, I think a number of VNs (that are made by companies or have a budget and are long enough) are usually around that size of 5 to 6 gb.
I've been looking through the files of a lot of them lately and I've seen it's not just the audio that's heavy, it's also the asset files (such as images) that contribute to the size. I've seen that it's usually like 2+ MB each for CGs for a lot of modern ones.
Also, there's some FDs have CGs and stuff from the previous game in its files, which mostly likely contributes to the file size. As MariPZ mentioned, the Virche FD is large. Piofiore's FD is like 6.5 to 7 gb large. 9 RIP has versions of CGs that one is 1920x1080 and the other one is double that size. Its sequel also kept both versions in its files lol. If they're gonna reuse assets and keep the files in, I wonder why they just don't make the FDs DLC instead... though they most likely want and need to get more money from their audience + more money in compilation lol.
Other than console games, I can expect mobile/gacha games to be heavy since they're obviously increasing in the size with every update lmao. I bet that Silent Whispers will be one of the largest, if not the largest, due to the usual size of open world gacha/online games.