We kind of need fewer consumption if we want to get anywhere near carbon neutrality. We don't have time to invent the future technology that will enable us to replace petrol everywhere. Hell, if that technology was invented already, we don't have enough time to replace our cars anyway. And even if we did, it would emit too much greenhouse gas just to manufacture all the new electric cars.
So yeah, in my humble opinion the only solution in the time that we have is, less cars, planes, boats...
Actually yes - climate breakdown is just one of literally thousands of causes of ecosystem collapse. It's the most dramatic, and in many cases (eg. the Great Barrier Reef) it's the coup de grace, but it's 'economic growth' per se that is incompatible with the continued existence of planetary life. Theoretically if human technology could approach the level of sophistication of complex evolved systems (biomimicry) we might achieve a truly circular economy, but that's a long way off. For now, economic growth just physically is the dismantling of ecosystems, and these systems are reaching the limits of their capacity to absorb insults.
So, yes, some combination of reduced consumption and/or population will be necessary even if this one issue of climate change is successfully tackled in time (distinctly doubtful at this stage).
You definitely need less people once you realize that most of Earth's population lives in developing or underdeveloped countries. Which means that as they progress consumption will skyrocket. India alone has more citizens than Europe and US combined.