Theres no hard and fast rule on this one, it will partially be that your feedback will earn more clout over time. It also helps thinking about the feedback you’re providing and thinking:
-Is it constructive? Can someone actively do something with my feedback?
-Is it objective or subjective? IE “This doesn’t leave enough room for the battery pack clearance” is a very clear objective piece of feedback. “This battery pack would be better designed with a harder crease in the surface” is subjective and more easy to shrug off.
-If you were given your same piece of feedback, how would it make you feel or react?
-Is it possible the design has other requirements you aren’t aware of? Ex: “This handle would feel much better with a rubber grip, but there is a cost constraint that prevents us from adding one”
Sometimes phrasing your feedback in a way that either asks some of those questions first (making sure you’re aware of what went into the design) will make others take feedback with a better appreciation that you understand the problem a bit more. In any design firm, this is always hard regardless of seniority especially on teams where some designers may only see a design once every few weeks, and not know the weeks of back and forth that went into the decision process.
Some designers also just suck at taking feedback, so don’t get discouraged it will develop with experience like the rest of the skills.