Want to know About theta

If I buy Nifty at strike price 1000CE and theta showed it’s value -3.08
My question is
If all Greeks are not changed what will be my premium for next day?
Total 75 ×(-3.08) = -231 will be reduced from my total value of option?

theoretically yes. You can learn more here on Varsity

Can check sensibull, they break down all premium into greeks and show exact values.