It may be possible to extend your Wi-Fi signal far enough to reach your in-laws' home, but it will depend on several factors such as the distance between the two houses, the physical layout of the area (e.g. the presence of walls, trees, and other obstructions), and the capabilities of your router.
One option to try is to purchase a wireless range extender, which can amplify and rebroadcast your existing Wi-Fi signal. This can help boost the signal and increase its range, allowing your in-laws to connect to your network from their home. You may also consider using a high-gain antenna to increase the range and power of the signal.
Another option is a wireless bridge, which allows you to connect two separate networks (one in your house and one in your in-laws) using wireless signal, this way you can extend the internet access to their home.
Please keep in mind that these solutions have range limitations, and an obstacle such as a big wall or a long distance could affect the signal strength, so the best approach is to try one of these options and see how the signal strength is and if there's a signal at all, if the signal is weak or unstable, you could try other options or even consider that this solution may not be possible for your specific case.
Additionally, it's important to check and make sure that there's no laws or regulations that are prohibiting the use of wifi signal on the area you want to extend the signal to, in some cases it's against laws to use wifi signal from different locations.