There are several real estate investment instruments available for NRIs and OCIs looking to invest in Indian real estate. Here are some of the most popular options:

1. Real Estate Investment Trusts (REITs): REITs are a popular investment instrument for NRIs and OCIs who want to invest in Indian real estate without directly owning property. REITs are regulated investment vehicles that invest in income-generating real estate assets such as office buildings, retail spaces, and residential apartments. NRIs and OCIs can invest in Indian REITs through the stock exchange.
2. Real Estate Mutual Funds (REMFs): REMFs are mutual funds that invest in real estate assets such as residential and commercial properties, and are managed by professional fund managers. NRIs and OCIs can invest in Indian REMFs through the stock exchange.
3. Direct Purchase of Property: NRIs and OCIs can purchase residential or commercial properties in India for self-use or investment purposes. They can also purchase land and construct a property on it. However, there are restrictions on the purchase of agricultural land, as mentioned earlier.
4. Joint Development Projects: NRIs and OCIs can participate in joint development projects with Indian developers where they can invest in the development of a property and share the profits or ownership of the property.
5. Real Estate Crowdfunding: Real estate crowdfunding platforms allow investors to pool their funds together to invest in real estate projects. NRIs and OCIs can invest in Indian real estate crowdfunding platforms that are authorized by the Securities and Exchange Board of India (SEBI).

Overall, there are several real estate investment instruments available for NRIs and OCIs looking to invest in Indian real estate. It is recommended that they seek professional advice from experts in real estate, taxation, and legal matters before making any investment decisions.