In the Stryd training with power manual (stryd.com/guide) you can find various target powers for events:
|Distance (km)||% 10k power|
Your event might be a different distance between 10k and 42.2k, and you can estimate your power for your event with the following formula (does not work for distances less than 10k):
% 10k power = -0.325 * race distance + 103.25
This is a simple linear estimation, and is not fully accurate.
If you have additional questions, contact firstname.lastname@example.org.