Prior to your Send Offline Conversion action step, create a filter to make sure that only conversions from Google Ads are added. You must have a GCLID in order to construct an offline conversion, thus make a condition that says only if it exists can the process continue.
If the conversion event you're tracking can occur within 24 hours of the time the ad was clicked, then you'll need to add a Delay For step to delay for 24 hours prior to your Send Offline Conversion action step.