Buy the game from the Epic Games Store or Steam, where it often goes on sale for very low prices.
If you are looking for legitimate smaller file sizes due to slow internet, the only safe options are "repacks" from verified community members: Gta 5 Highly Compressed 10mb For Pc
Given the clear impossibility, why do millions of people search for “GTA 5 highly compressed 10mb for pc” every month? Buy the game from the Epic Games Store