Extension v.s. KDNR increase your house value(land excl.)?

hi ,
I am new here, and just started my journey.

We have a 930qm land in upper north kuringai council on a 1~1.5m sideway fall land. Our land is pretty good, not many trees, but our house is like 50~60yrs old dual brick, and small (one storey).

The things i don't like most is our house is sitting side angled so my yard is not rec-tangled therefore it looks not as big as it should be. Plus it's too small for our growing family

I am thinking of extension vs. KDNR.

1) If I just extend a sunroom(5*3m), enclose my double car port, backyard paveway, basic landscaping of the yard, i guess i could probably end up spending 200k all included. But I don't think it bring my house value up. is it worth to do such work on this old house?

2) according to my recent research at Homeworld comparing different pricing, I probably need to budget all in 700K~800K for a 35 SQ house with a project builder ( currently looking at claredon, wisedom home). Anyone has experience how much roughly house value would increase? if we are to sell it , would we possibly making some profit from the house itself(not the land value growth)? My land bought 5 yrs ago, so I paid quite a bit. I feel quite stuck here. if I have enough financials, i would love to KDNR asap but it's quite a financial pressure for us. If unfortunately either me or hubby got redundant, worst case we have to sell it.

3)If we just sell the house as is, my land value has grew roughly 15%. i could probably capitalize it by doing nothing. if KDNR don't grow much value, why all the efforts?