How do you handle default preview settings?

[ddbrierton]

I'm very new to using fzf, still feeling my way in terms of default settings. I get why it's not a good idea to put preview options in FZF_DEFAULT_OPTS as there may be cases where you don't want any preview at all, and obviously how you might want to preview git branches might be totally different to how you preview a file's contents, but then it's also a pain to have to manually type out

--preview "bat --color=always {}"

Even if you create aliases for all your most common invocations of fzf, that doesn't cover ad hoc use cases.

It would be nice to be able to type something like

--preview true

or

--preview false

and then have separate environment variables for your preferences for how to preview file contents, directories, git branches, etc.

For those of us who may not be particularly expert at shell-scripting, what are the recommended ways to set this up?