Take out the thermostat and see if that helps sometimes you get bad new parts you will need a thermostat in the winter or you won’t get heat

Check your engine oil, if it’s a milky coloured then you may have head gasket concerns , also see if your cooling fan for the radiator are coming on. As mentioned in the above post , there could be air trapped in the system, you’ll want to make sure that is purged.also have you inspected/replaced the rad cap , it may be faulty, caps can be tested or you can replace, not overly expensive

Might be air in the system