Can someone tell me if this is a fiberglass pool??

Looks like either cement or pool vinyl liner, can't tell if it's fiberglass by the picture

I've seen fiberglass pools in simular shapes. I'd start a Google search of pool co in your area

This pool looks to be installed the traditional old fashioned way with concrete. But . . . You can get fiberglass pools. I would visit pool stores in your area to see what they have to offer as well as interview a number of professional pool builders. There are also kits you can purchase on line and have your builder install. Compare the cost of traditional concrete v. other options. Your location and weather is a factor too, see what might be best before making a decision.

This is absolutely beautiful! I would be falling all over myself to have a yard this big with such a resort in my backyard. I would never leave my house except for groceries . . .

https://www.popularmechanics.com/home/outdoor-projects/how-to/a3482/4276117/

https://www.riverpoolsandspas.com/cost

https://www.poolwarehouse.com/fiberglass-swimming-pool-kits/

It is possible that it's fiberglass. There are so many styles now. Keep in mind that that backyard cost over $100,000. So I hope you've saved your pennies, nickels, dimes, quarters and lots of dollars too. My daughter put in a pool (gunite) and had a structure built for her outdoor kitchen and some seating, and a firepit. That was also over that price point.

Looks like a custom gunite pool to me

It looks like a concrete pool to me. I don't know if you could get a pool shaped like that out of fiberglass.