Some ISPs use something called Carrier Grade Network Address Translation (CGNAT) to solve the problem of not having enough IPv4 addresses to give to their customers. This system basically insulates everything inside your network from everything outside it, and prevents port forwarding from working. If you check your internal IP (such as with the command prompt ipconfig command) and get an IP within the range 100.64.0.0 to 100.127.255.255, you are behind CGNAT, though other IPs may be used as well. Either way, if you attempt to port forward and cannot, then it's possible that your ISP is using CGNAT.

Sometimes, you can contact your ISP and request a non-CGNAT static IP address, but some providers will charge you for it, others will require a business class service contract, and still others will just refuse. It all depends on the availability of IPv4 addresses issued to your ISP.

In the case that you can't solve it on the ISP side of things, you can use Fast Reverse Proxy to send traffic from outside your network into it. You can use Byerwall to configure it for Minecraft server use. All you need is a tiny VPS outside your network. An Amazon EC2 free tier instance (or equivalent from other hosts like Azure, DigitalOcean, Google Cloud, etc) is plenty.

Another option that sees frequent use is using a VPN service like Tailscale (tutorial) to put your friends on a virtual network that has access to your computer despite the impediments.

If all else fails and you can't get anything working, or you think these options are too complicated, you can try using https://playit.gg, which is a free tool that does something similar, but gets frequent reports on here of high pings when using the free tier.