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Use the setItems() method as validation script in the first dropdown.  I developed a (paid for) tool that writes the code for you after you copy and paste the lists from an Excel column into the windows, if you're interested, as well as another (paid for) tool that lets you load dropdown items by copying and pasting Excel column(s).

Yes, this can be done using a script. The basic code is this (to be used as the custom Validation script of the first field):

if (event.value=="Option 1") this.getField("Dropdown2").setItems(["Item 1", "Item 2", "Item 3"]);
else if (event.value=="Option 2") this.getField("Dropdown2").setItems(["Item 4", "Item 5"]);
// etc.
else this.getField("Dropdown2").clearItems();

If you're interested, I created a (paid-for) tool that will allow you to set it all up in seconds, based on a data file, without having to write any code: https://www.try67.com/tool/acrobat-create-dependent-dropdowns