Question regarding dhcp client setting

If I set my router as a dhcp client, can I still assign it a static ip so I can access it? If so, will I have to assign it my mac id from my main router?

Mixed info, not enough info on network/device topology...
router, main router...
why mac id???

If you have several routers inside the same LAN, it might be best to connect them via LAN ports and just assign a fixed IP address for the "secondary" router.

If you talk about new router's WAN connection, that should likely be left as DHCP in case the router fetches WAN IP address from a DHCP server. And you likely will access the router via LAN for which you should set a fixed IP.

Even in case you set the router as DHCP client also for LAN, you should then access the router using that address (which you can see from the main router's DHCP server logs)

Cable modem to main router wan port. Lan port from main router to secondary router (ideally wan port to free up lan ports for other devices).

The secondary router I have now isn't giving out dhcp ip's or forwarding dhcp ip's from the main router. I've tried both the wan and lan ports on the secondary router. It is running lede.

Under the network-interface-lan I have it set as static ip with the box for disable dhcp for this interface checked.

I'm wondering if I set it to dhcp client it will start forwarding dhcp requests from the main router. I still want to access it though which is why I will give it a static ip using it's mac address from my main router.

The easy solution is to sacrifice one LAN port on the secondary router, connect via that LAN port to the main router, and dumb down this secondary router (no DHCP server etc).

I gave you advice for that in Help installing packages, Failed to establish connection but pc internet works fine when connected to router

Other configs are possible, but you need to have basic understanding of the various network components and services first, and I am not sure you have those yet. Router using DHCP client for getting its own WAN address is quite separate from it acting as DHCP server for LAN.

Is there anything I can read that would help clarify it further?

This is my first router with lede and it seems a little more complicated than dd-wrt where all I had to do was this https://www.dd-wrt.com/wiki/index.php/Wireless_Access_Point#LAN_Uplink_Through_WAN_Port

You cited the reference in your other post
https://wiki.openwrt.org/doc/recipes/dumbap

At one point I did some docu for LEDE based on the above, but it's only "Playground" .
https://lede-project.org/playground/qsg_lede_installation_guide?s[]=dumb&s[]=ap

I would only set an IP on the AP, and not main router. This guarantees you can access the device standalone.