I got a list that I purposefully set up to grow. It's not a to-do list... It's a "might do" list. When things get messy in my to-do list, I move those items to the might-do list.
Having 100 undone items on that list isn't a shameful thing, it means I said "no" to all those items (either actively or passively) and I try to celebrate that.
Multiple lists. Short-term, medium-term, long-term, "maybe eventually". If one of them starts to feel like too much, I can kick some things down to the next one.
They're also kinda based on how much focus will be needed to complete things, not just how important or time-sensitive things are. The medium/long lists are mostly stuff for "good brain days".