二次元

https://www.52yih.com/apis/random/api.php
Sakura主题默认随机图api
https://acg.toubiec.cn/random.php
https://acg.yanwz.cn/api.php

人物风景

https://source.unsplash.com/random
https://unsplash.it/1600/900?random

Q.E.D.