If a flight on any airline (US domestic or foreign) is scheduled to depart from a US or arrive at a US airport and the flight schedule significantly changes, the airline must refund your money in full if asked, regardless of the type of ticket you bought (including basic economy).
Examples:
you bought the non-stop from Cleveland to Madrid but that plane didn't fill up so they cancelled your flight and rerouted you Cleveland- Chicago- Madrid. You can keep the reroute for the same price you paid or ask for a refund.
you bought the Tuesday flight and they cancelled it and rebooked you on Wednesday. Accept the new flight or ask for a refund.
They changed the departure or arrival times by (I think) it is 4 hours. They shortened a connection time.
All of the above qualify for a full refund, regardless of what kind of ticket you bought, including basic economy.
Here's the fun parts- if YOU cancel your flight, no refund is guaranteed and certainly no reschedule at the same price you originally paid. Most airlines will try to offer you a voucher instead of a refund and then qualify it to be used in a certain time. Better to read the Contract of Carriage that is included in the Terms and Conditions of every ticket and be ready to quote it if needed (which I one time had to do). TAP was notorious at the start of Covid for refusing cash refunds but also dawdling on credits. They have had a tremendous amount of very inexpensive fares advertised in the US in the last 30 days, but I chose not to book based on their refund history in 2020. And the most fun of all, if you bought your ticket thru a third party online travel agency such as Expedia, Kayak, Priceline and the like, most airlines will require you to go thru the agency you bought it from to handle any refunds/credits as the agency is technically their customer, not you. And all of a sudden, the 40 bucks saved booking with an online travel agency vs direct with an airline doesn't look so good. I always book flights direct with the airline.
There is one piece of good news and that is that kindness, positivity, and initiative can work in your favor. You are always able to call the airline and in the nicest way tell them that the flight you booked was cancelled/changed/rerouted/whatever and you know you are entitled to ask for a refund but you really want to go on the trip you have planned instead, would they be able to get you a seat on the (flight you already looked up so the customer service agent doesn't have to) set of flights instead so you can take your planned trip? I'd avoid the words rebook or reticket as those have very specific meanings in travel-land. Be kind and vague. This successfully worked for me earlier this year in getting a ridiculously discounted ticket moved from March to September for a country that hasn't yet reopened.