a custom search string URL may be what you're looking for

for example, I use the following with the Fennec fork of Firefox Android to restrict the date to before the public launch of ChatGPT, while simultaneously disabling DuckDuckGo's AI features:

https://noai.duckduckgo.com/?q=%25s&df=1979-01-01..2022-11-29

here's DDG's guide on search URL parameters; most major search engines should have similar documentation

You could write a bash script to do it and perform searches from the terminal. It will open a new tab or window in your browser with the term you entered with the appropriate settings. Then set the bash script as an alias to make it easier to use. I found a similar script and modified it for ddg. doesn't seem to work 100% though, per usual it works on my machine, as-is no warranty, you need to install jq first if you already haven't.

#!/bin/bash

# Check if a search term was provided
if [ -z "$1" ]; then
    echo "Usage: $0 <search_term>"
    exit 1
fi

# URL encode the search term (handles spaces and special characters)
encoded_search=$(printf '%s' "$1" | jq -sRr @uri)

# Construct the DuckDuckGo search URL with a date filter for content before Jan 1, 2020
duckduckgo_url="https://duckduckgo.com/?q=%24encoded_search&ia=web&t=h_&df=on&dfdate=before-2020-01-01"

# Open the URL in a new browser tab (works with most common browsers)
xdg-open "$duckduckgo_url" 2>/dev/null || open "$duckduckgo_url"