Refer https://incometaxindia.gov.in/Tutorials/15-%20LTCG.pdf
Page: 6
"Note: The Finance (No. 2) Act, 2024 removed the indexation benefit and introduced a
uniform tax rate of 12.5% on long-term capital gains. As per the amendment, no indexation
benefit is allowed while computing capital gain from long-term capital assets transferred on
or after 23-07-2024. However, the Government has introduced a grandfathering provision.
This provision allows resident individuals and resident HUFs to still apply indexation on
land or building acquired before 23-07-2024 and pay tax at the old rate of 20% if the tax
under the new law (i.e., tax calculated at 12.5% without indexation benefit) results in a
higher amount."
Also read the illustration given on page 8-9 for better understanding.