is it possible to bold part of the SMS content?
There is option right click/Format/Bold but it is available only for emails.
You can not send an sms with bold content. SMS is text only. You can achieve that using a MMS.
Adobe Campaign has removed this feature, check with your CSM if you can still use it.
Note: Some devices still supports limited feature check if they support *bold* or <b>Bold</b>
Generally, this is used for MMS delivery as we use SMS channel for text and add picture/gif as attachment.
My idea was to see can form itself achieve bolding in order to avoid handling this in connector code.
<b>Some text</b> is working nice in the Preview tab, but it is sent like that so on the phone you receive <b>Some text</b> with tags.