You don’t “need” to know expressions to do what you’re asking. They just help you manipulate things faster.
Most “film-look” effects have some sort of value control to fade off the effects. For example, BCC’s effect called Film Damage has grain, dirt, hair, and scratches. Each one of those elements has either an “amount” or “density” value. So for each one, make a keyframe at the beginning of your fade using your desired value amount and then at the end of your fade, bring them all down to zero.
Expressions allow you to link all of these to one controller layer, which makes for quicker manipulation. Don’t get me wrong, you should learn expressions, but they aren’t totally necessary to accomplish what you want.
Hope this helps.
-Kevin
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