Maybe, these are buses organised by the railways. If you provide details of your connections with bus, then a more precise answer is hopefully possible.

Check the interrail map, there are some (very few!) bus lines marked that are included.

And, if it is a replacement bus for a train that is included, it is also included.

Normal citybuses are never ever included, but will also not break the bank. More troublesome for many nowadays is, that often cash payment on bus is no more and one needs to make inquisite enquiries as to how even get a ticket (f.e. in Barcelona it means loading an app and paying with that QR code delivered!). But nearly all large cities that makes you to switch between trainstations have metro/underground (London, Paris, Milano spring to my mind)