Need help to xiaomi r4a increase file system storage

Hi all
I have xiaomi r4a gigabit edition router.
It has 7mb filesystem and 58mb temp storage

I need to increase file system storage.
I tried this method bur not worked:
https://openwrt.org/docs/guide-user/advanced/expand_root
i did same as: https://www.youtube.com/watch?v=OSx_HDMaHXo

What can i do?

The usual approach is to plug in a USB drive, however this model has no USB port, so you are limited to the small internal chip. You might gain a couple of MB by using owut or the Firmware Selector to cram down your installed packages into the ROM (which is compressed more efficiently) instead of jffs.

Temp storage is a RAM disk. Files there are erased in a power cut or reboot.

Can i take 10-15 mb to file system from temp?

What should i do with firmware selector? Should i remove some preinstalled apps? or should i add what i want to its code?

Temp storage is ram disk. You can install packages there until reboot by using -d ram parameter to opkg and adding lib path and program path.
You can use luci-app-attendedsysupgrade for more comfortable selector frontend.