Is it possible to go back to 7.6?
If you have a locked bootloader I don’t think so. If not, then depending on your device you could switch slots.
Use fastboot getvar all in a commandline if you have a slot a and b.
Typically “no”, Android is not happy with going backward (not just if the bootloader is locked which could trigger “Anti Rollback” or ARB: but the system and apps used in combo with your userdata all get configured to use the newer system and it could be quite unreliable to “pull the rug out” from under them and try to get them behaving well on an older build). Is the motivation only AntennaPod (from your other thread)?
The IS update was not responsible for my issue with antenna pod.
Which is good because it seems Downgrading is not a good idea.