If I buy the game on PS4 will I have it on Ps5?

There are some caveats to PS5 backwards compatible functionality - which is explained in the next section - but in short, every PS4 game but the following should work on PS5:

DWVR
Afro Samurai 2 Revenge of Kuma Volume One
TT Isle of Man - Ride on the Edge 2
Just Deal With It!
Shadow Complex Remastered
Robinson: The Journey
We Sing
Hitman Go: Definitive Edition
Shadwen
Joe's Diner

This means if a game isn't listed above, it will be playable on PS5. This includes PSVR titles and those which require the use of PlayStation Move, or the PlayStation Camera - though the PS5's own HD Camera will not work with PS4 games.
Source-https://www.eurogamer.net/articles/ps5-backwards-compatibility-ps4-compatible-playstation-6300
So yes HP2010 HD will be playable on PS5 since it's not one of the dropped PS4 titles listed above.

@2ELI0 Thanks a lot i have searched everywhere to be sure that we can use it on ps5

Thanks 🙏