Depends on the time period you are aiming for.

Early war US. So 1941 phillipines and other early battles against Japan only Signals corp had radios. As most tabletop games usually portray a single platoon reinforced by battalion support you could say a radio operator would appear here, but unlikely.

1942 there were a few "pre war" models issued to troops, if numbers allowed at company level however these earliest models were quite heavy and difficult to use even when backpack mounted. Most tabletop miniature kits wouldn't have parts of these models because of how big and rare they were. Also it seems most miniature makers only care about D-day and onwards.

The biggest jump forward was the SCR-300 backpack "walkie talkie" that was first used in the invasion of italy in August 1943. They were flown to europe as shipping would take too long and they were considered high priority. This is the backpack radio that is seen in all those photos and was used for the rest of the war. If supplies were available they would be issued at a company level and by Normandy there were enough units available.

I can't say when they first reached the pacific but like everything the first units suffered heat, moisture and mould problems that were solved eventually.

The other radio you might be interested in is the SCR-536 "handy talkie". Handheld radio entered production July 1941 and first used by US forces in north africa in November 1942. Being handheld range, power and effectiveness was limited compared to the backpack radios, but it was better than nothing.

A rifle company would have 6. 3 infantry platoons, 2 for the weapons platoon and 1 for the company commander.

It should also be noted that only US forces had handheld radios, and only they would have radios at a platoon level as standard equipment. This gave the US army significantly better unit communication and coordination.