external sd - How to free Internal Storage by moving data or using symlink / bind-mount with Adoptable Storage?

Galaxy S5 running LineageOS 16 (Android 9).

I'm having issues with running out of storage space, even though I have 128GB external SD card, merged with the internal storage. Is there a way to create a symlink from the internal memory to the external SD card, even though they are technically merged and aren't identified as separate storage locations within Android as a result?

I've never made symlinks on Android so I'd appreciate some pointers or resources on that as well.