Debt Mutual Fund Tax in New Regime

I have bought Debt Mutual Funds in 2020 and I sold them in 2025.  I want to know the following from others whether my understanding of Tax is correct.

1. The Debt Mutual Funds was bought in Dec 2020 and the same is sold in Dec 2025.  I have held the Debt MF for more then 36 months.  I would like to know whether Indextation benefit is applicalbe/available for the same and whether I need to pay only 20% tax after the Indextation benefit is adjusted.  I am planning to use the NEW Regime while filing the tax statement.
2. Please let me know whether my above understanding is correct.  If not, what is the actual tax applicable.

Thank you in advance to all.