How to combine 2 routers with different providers into a single local network?

Question

network hardware

Good afternoon.
Description: 2 cables with the Internet from different providers are brought into one room. There are 2 TP-Link Archer C20 routers, each has its own cable connected, respectively. N devices are connected to each router (via LAN and via Wi-Fi).
Bottom line: how to combine these 2 routers and all devices connected to them into a single local network? The ability to connect routers with a cable is available.
PS I don't really understand this topic, so I'm asking for help. If you need any nuances to solve the problem, write. Thanks in advance.