Hi,

I’m just a 240 man but a coolant system is just a hydronic system and air entrapment will all be the same.

All it needs is an opening along the highest point of the system. If you live back east where these type heating systems are very prevalent the radiators have devices that you are expecting to find,
But on cars it’s the recovery bottle cap or the radiator cap that does the venting.

What you might try is to just loosen the cap a wee bit while the engine is heating up and until it reaches operating temperature.
You don’t want to leave it loose as most systems require the coolant to be held under some pressure to raise the amount of heat that the coolant can carry per pound or gallons if you want to think that way.
Both are figured on the amount needed for expect heat transfer. The radiator is also sized accordingly with fans and other tricks used within limited spaces. Plug in weight considerations and a Manufacturing budget, the bleeder valve is optional.
I think I have read that on BMWs nowadays and it must be located at the highest point. Very near the filler port. It’s not much of a gadget but their engineering left them no option but you cannot get all the coolant in it without it.
They always have sneaky tricks under the hood that has scared me away from ever owning one. The newest Volvos have moved into that category too.

If it’s got one you should find it near the same places, up high.

Phil