This is what I'll be using for most (if not all) of my sound effects; it's a great resource. They've been releasing a free pack every year, and they have archives going back to 2015.
Additionally, I've trimmed/modified a handful of these sounds to more immediately usable, so feel free to use them if you want.
some trimmed/modified sonniss sfx
Finally, if you need music then the YouTube Audio Library is a good option.