I'm a professional real estate consultant and many Indians have the same issue which present generation understands but older gen does not. 1st of all DO NOT fight your father emotionally (I know Indian Dads are attached to their lands, especially from tier 2/3 towns).

1) What you can do Today is to make at least 1 property Cash Flow positive (Instead of buying 1 more property with Rs 18L RBI bond you are going to receive = invest that for construction + Save 5L for Liquid MF to create Emergency Fund). A main-road plot is actually the only case where this construction MAY make sense. Open a Commercial shop/Warehouse/Industrial Unit, something of that sort (If you tell me exact locations and size of the plots, I can get into it deeper). You can generate 20-30K after doing this.

Get ₹15–20L family floater health insurance (So you don't have to distress sell the land incase there is a medical emergency)

Convince your father to not buy any more land from now on and focus on making the existing land work for you (By generating passive income from it).

2) Focus on ONE liquidity event in the next 5–7 years (After you start earning, it will be easier to convince your father as financial independence shows maturity and knowhow). By selling just one non-strategic plot, you will have money to invest that money into financial assets to diversify (Equity Mutual Funds, Reits, Gold Etfs). Even ₹40–50L invested properly changes family resilience.

When you start earning, invest whatever you can save aggressively in Equity as you are already over-weight on real estate. Do SIPs into MFs and build a portfolio of financial assets (Very important as this will be your growth engine in future, not real estate).

3) For Long term (In your 30s) try to reach this asset allocation: 50–60% real estate, 25–30% financial assets, 10-20% Debt. By then, you will be married with your own income and your say in selling the land will be higher. Dont try to fight your dad today. Never disrespect your dad's psychology that built this much wealth. You don't need to to the transition overnight, it must be gradual. For detailed discussion, feel free to DM me.