Landed House A&A, Reconstruct or New Build? And Property tax.

Hi All, my first post. My question doesn't fit in any of the forum categories so I'm hoping someone who's been through this can share some light.

I have an old original 70 year old semi-D (land 4800, build up 1400 estimated). Currently thinking of either A&A (50% additional floor area), reconstruct, or going the full new erection route. As annual value and corresponding property taxes skyrocketed so much this year, I feel it has become a factor in the decision of what kind of Reno to opt for. And most importantly, whether we'll be able to afford paying those taxes in our retirement years. Does AV and property tax increase as per the square footage increment or does it change according to the choice of A&A/reconstruct/new build? I have a neighbour who advised that I should just do A&A and he has done this to the max 50% additional floor area. His AV is in the $50k range. Mine is in the $30k region. Another neighbour who did a new build to 7000sqft has an AV above $150k. Is it true that property tax for reconstruction/new build shoots up exponentially over A&A? And if going for new build, will choice of detached vs keeping it semi-D affect the AV?