Unless your plants are already in pots or you can get/build a simple greenhouse, you won’t be able to do much with the grown plants.
If you are unwilling to give up just yet, get some wood and foil and build a “rain shelter” type of mini-greenhouse like this one (random example, not a specific recommendation) or see if your local garden center has those oversized plastic bags with holes that are mainly used to protect the plants from rain. With a bit of luck, you’ll manage to get at least some fruit if the plants have already set fruit. If you have only flowers, you’ll need a very long and warm autumn. (And you have to ensure that the flowers are pollinated, so shake the plants, get a paintbrush and play bee, or remove the cover when it’s warm enough.)
If you decide to go that route, you need to make it clear for your plants that it needs to put its energy into the fruit, so cut the tips of the plants off, remove the suckers and leave maybe two or three (or less?) fruit branches per plant.
You can make tomato cuttings, but not the way your question implies you are hoping for. Tomato cuttings are made with the suckers that are typically removed from the main plant anyway and the rules for all cuttings apply: Remove everything that draws energy from the baby plant, i.e. flowers, fruits and excess leaves. Simply cutting your plants in half and expect them to grow roots and fruit at the same time won’t work. If you want to give it a try, you could do the cuttings now (or just before frost kills your plants) overwinter them indoors and get a serious head start. Rooting in a jar of water or directly in potting soil should work. You may have to repeat the exercise though, to have young plants ready once the outdoor tomato season starts in your area.
Not part of your question but maybe worth thinking about is why are your plants so late? Ok, so if you were super late in sowing the seeds or buying the plants, you’ll already know what to do next time. If your have a very short growing season, growing the plants in pots can give you a head start in spring and allows to take them inside if autumn comes early. But if all of that’s not the case, your description of “tall and robust” plants could be a hint: Check your fertilizer composition. Yes, tomatoes are “hungry” plants but if your fertilizer has too much nitrogen, you’ll get great growth and foliage - but little fruit. This is a bit of a “stab in the dark”, but may be worth checking.
