Managing feelings of autonomy under my boss

My question is based around a model I worked through with a coach:

Not feeling autonomous under my boss and this affecting my enjoyment of my work

Boss called me and told me that she wants me to take over her role in a meeting because she is unable to make it

I’m not being considered in the decision making

Disrespected. Leading to a feeling of defensiveness

Current: Raised my concerns (from a place of defensiveness) in an attempt of changing her mind/suggesting to her that she should pick someone else to go. “Tip toeing” around the issue rather than being direct due to fears of the outcome of being assertive. Hoping that she would be open to discussion around a different decision.
→ this is a step I have taken toward respecting myself. Previously, I wouldn’t take a stance and would have agreed with her decision.

My boss negated the concerns I raised (“don’t worry”) and stuck by her decision.
I felt disappointment and as this has been a repeated issue. I feel resentment and unhappy about my circumstances at work

What is my goal? “For her to respect me” → BUT I don’t have control of that. What I do have control over is respecting myself.
My conclusions are that in future, after feeling disrespected by my boss, instead of acting from a place of “defending myself”, I can consciously choose to create the feeling of respecting myself and take action from that place instead.
Potential inner dialogue: “If I’m respecting myself and if I feel love for myself, what would I say? What boundaries would I set?”

My questions based on this model:
1) Any feedback on this model/situation and how I could take action to overcome this recurring issue?
2) Practical steps to create feelings of respect for myself in the moment during the conversations with my boss? Find it challenging because of the power differential between us during the conversation.

Thank you in advance for your input!