dog pussy feels actually feels great. Warm, wet, and for most people tight. They do squeeze their vaginal muscles during sex, some squeeze harder than others. Vagina sizes will also differ between girls. But the sensation isn't really clamping, it's more like a gentle pulsing sensation, at least it is with my girl. Some girls will squeeze when you slide in while others will squeeze as your sliding out. My girl like to squeeze while I slide in.
The vagina will not actively try to push your dick out, no. Hold out your index finger and then wrap your other hand around it and gently pulse the other hand. That's about what it's like, just warm, wet, and on your dick.