It's been awhile since I watched it, but this anime (based on a manga) is worth checking out if you're a fan of breast expansion and breast reduction.
Manyuu Hikenchou: https://en.wikipedia.org/wiki/Many%C5%AB_Hiken-ch%C5%8D
[mild to moderate spoilers]Due to the era it's set in, it reminds me a bit of a Japanese version of Xena: The Warrior Princess. It's silly but also has its serious moments and has a heart. I haven't read the manga it's based on but the series has story elements and world building that I've always wanted to see explored, particularly what would happen in a breast-obsessed society where having large breasts is rewarded. I like seeing how large breast propaganda would affect society and people's day-to-day life. It explores the pros and cons of having large and small breasts and the unfairness of this system. There's breast envy, characters who actually like or want small breasts, and those who feel burdened by large breasts.[/spoilers]
I'm likely overselling it at this point as there's only one season but the world building feels like it was written for me in some aspects so I just thought I would share for those interested in similar themes.