At this time there is no M5 iMac available, announced, or predicted. There is no M6 yet either, but I would expect to see one perhaps.
The usual model has an M4 chip with 10 cores and a 24 inch display. The base price is $2099 with 24G of ram and 512G of SSD. The 10 core CPU comes with 4 thunderbolt ports, but you can save some money with a 10 core CPU and 4 thunderbolt ports.
The display is 24 inches and 4.5K (4480 by 2520). It runs at 60 Hz and claims 500 nits. It is an IPS panel.
You could also save money with less ram (16G). Currently more ram (32G) is unavailable.
You can bump up the SSD to 1T for $300 (or to 2T for $800)
You get a 1G ethernet and no choices.