If you buy the Sonatinis from a distributor, they should be prepped and ready to bloom. I usually get mine right from the grower in The Netherlands and they don't harvest bulbs until about this time of year....then they condition them and ship them in late winter early spring. Since the grower is in the same hemisphere as the US, the bulbs are in schedule for spring blooming. Bulbs that you can buy that are grown in South Africa or South America typically ship starting in October and will be ready to bloom because the seasons are reversed for them and they are conditioned to bloom in their spring, which is now. They were dug up months ago and have been refrigerated by the distributors to delay blooms for up to several months.

I'm not sure what a regular amaryllis is...

My sonatini bulbs were just dug up from the garden. Can these be forced indoors? I guess the "regular" amaryillis I mean are the ones sold in store for forced indoor blooming during winter.

You can try. I would chill them for a couple of months and the bring out to good light and water once. I think 48 degrees is optimal for cooling. But dark snd cool are keys.