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It is likely that many of them will survive. Just treat them as you would when overwintering larger plants.

Letting them dormant, as you are wanting to do, is best. This article will help:

https://www.gardeningknowhow.com/ornamental/flowers/geranium/geranium-care.htm

This collection of articles will offer more information:

https://www.gardeningknowhow.com/ornamental/flowers/geranium

Perennial geraniums, also called cranesbill, will produce seed if you don't deadhead the flowers at the end of summer. The seedpods are elongated and start out green, then change to brownish when ripe. It's important to harvest the seedpods before they "explode" or the seeds will be lost to the wind. You can enclose the pods in mesh bags to prevent that from happening. They must be able to get sunlight, however, so nothing opaque. Once you collect the pods, leave them in a dry, warm area till the pods split, revealing the seeds.

Here is how to germinate the seeds:

https://www.gardeningknowhow.com/ornamental/flowers/geranium/geranium-seed-propagation.htm

During winter, care for indoor geraniums by placing them in a bright location with indirect sunlight. Allow the soil to dry between waterings to prevent root rot, and maintain a cool indoor temperature, ideally between 45-55°F (7-13°C). Trim back leggy or dead growth, and consider reducing fertilization to once a month. Keep an eye for pests and ensure proper ventilation to promote overall health during the winter months. You can also force dormancy, which is another good way to overwinter them.

https://www.gardeningknowhow.com/ornamental/flowers/geranium/how-to-save-geraniums-over-the-winter.htm

https://www.gardeningknowhow.com/ornamental/flowers/geranium