I think it's safe to say that Notion's grace note capabilities are restricted to standard notation of not-too specialized music. According to Kurt Stone's book on notation (Music Notation in the Twentieth Century), it is no longer considered necessary to place a slur (not a tie) between a grace note and the following pitch. Nevertheless, Notion allows you to slur grace notes: Tap on Select, highlight grace note and main note, and tap the slur icon at the far left of the sub-toolbar.
If you are looking to create a baroque-style Acciaccatura, you'll need to write it out as standard notation. The Acciaccatura starts
on the beat, not before the beat, as "modern" grace notes do. The same wikipedia article on Ornaments shows you how to do this:
- 150px-Acciaccatura_execution.png (4.13 KiB) Viewed 10248 times
Best,
Thorrild