As per the title, pressing spacebar when playing pauses, it doesn't stop like it would in a DAW.
As you surely know, normal play and stop (without moving the playback position to the beginning) is toggled with the spacebar.
There is a keyboard shortcut for moving the playback position to the beginning, and that is Ctrl+[ for Windows and Cmd+[ for Mac. You could use that shortcut every time you stop playback with the space bar to return to the beginning.
If you keep the first note or another element at the very beginning selected, then pressing P instead of space to start playback will start from whatever you have selected.
I can't find a setting to default to always returning the playback position to the start of the score.
There is one more shortcut but I'm not sure what it does (it's not described in the manual). To "replay" (whatever that means), press Ctrl+Space on Windows or Option+Space on Mac. It might be that "replay" starts playback from the last place you started playback.