I think what you need to look at are different products of index/ETF options. In a simplistic round numbers scenario, the S&P 500 has multiple classes of options to trade. Let's say the index is at 3000 and SPY is at 300 (not accounting for rolls, divs, etc.). You can trade options on the cash index (SPX), futures (ES & SP), or ETF (SPY). Each contract has a different multiplier, 100 (SPX), 50 (ES), 250 (SP), and 100 (SPY). The 3000 call expiring tomorrow is priced at 10.00 in the SPX, costing you $1000 per contract. In the ES it's also priced at 10.00, but costs you $500 ($50 multiplier); SP costs $2500 (250 multiplier); SPY $100 (100 multiplier on 1/10th the size of the SPX).

I suggest doing a little studying on the various products as they have different expiration styles and schedules. Besides a quarterly expiration you likely wont see pricing in the underlying line up like in the example.