While each service is a bit different in terms of unlocking times, all of the Tracfone brands (Tracfone, Total, Straight Talk, etc.) are pretty easygoing if you activate on a Verizon-based SIM. For that you'll need to keep service active for at least a month and there are numerous reports that you can let it lapse and then on the 60th day, it will automatically unlock (you'd probably need Wi-Fi access for it to get the updated policy from Apple).
Other than the cost of one month of service and the time, it's a great way to get a spare iPhone inexpensively.
I did this with a Total back in 2023 for a second-gen SE, it's now unlocked and can work on any carrier. Sometimes you can get them for $99 or $149 (what I'm seeing right now), if you're willing to go to a Walmart location and buy them. They'll typically just stick a little envelope with a SIM card on the back and you can activate it yourself at home.