Since any business can implement HTTPS decryption on their own network, I would assume they can see everything you transmit using their assets. It requires minimal configuration on the client end, so even your own devices can be roped into the scheme too, if, for example, you ran a setup tool from IT or a web portal. This need only be a run-once-and-forget which installs their certificate.
In practice, it is highly unlikely that anyone will look at what you are sending. At most, they will review the traffic data in bulk to see what their employees are doing. However, your activity may raise a reg flag, or your IT staff may be nosy.
If you are on a company device, they absolutely can do it, and there is not much you can do to prevent it. You can conceivably work around it on your own device (e.g., with a VPN), if that traffic is not blocked. Technically and legally, in the US it is not much of a challenge for them.