“Starvation mode” is a bit of a misnomer or at the very least its actual effect is often overinflated. It’s important to make the distinction that as we lose weight our bodies naturally need less energy, even fat takes some calories to maintain. So the idea of a starvation mode is unnatural or disproportionate reduction in metabolism for someone’s now smaller size.
Given a long enough time eventually the body will start to adapt its resting metabolism to lower calories, though IF does help to insulate from this somewhat by not putting the body into the awkward spot of being in a deficit while insulin levels are still high often from eating all the time. Even if the body does adapt, it’s not like someone will suddenly start gaining weight on a reduced calorie count.
If you’re really concerned about it. Don’t deficit more than something like 1,000 calories. As someone else mentioned, take a few days every couple weeks to eat at or slightly above maintenance. Eat a high level of protein. And the most effective thing is resistance training. Doesn’t even need to Olympic barbell lifts or anything, simple bodyweight routines will suffice.