Do you mean message history when setting up a new device? They are working on that, but it’s not so easy to do without storing all your chats with a server side encryption key. Apparently something coming soon though.
https://support.signal.org/hc/en-us/articles/360007062012-Ne...
Maybe this is an okay trade-off for you, but Signal's phone number as ID requirement means they can rely on the local contacts kept on your device and keep very little metadata about you on their servers.