My 11 month old went into the vet alone last month and did not consent to being examined. The vet said she was "a bit snappy" and that they tried to muzzle her, but that she wouldn't accept that either, so they used a rolled up towel around her neck, which they said calmed her and prevented her from biting..She didn't seem concerned about her snapping and appreciated that she didn't know them and was alone.
I had to take her again today (to a different branch) and due to that memory she was very reluctant to go in, but thankfully due to Covid restrictions being lifted here in the UK I was allowed in with her. The vet asked me to put one hand under her chin/jaw and to hold her collar with the other while she was examined. There was a small growl when the thermometer went into her back passage (can't blame her!) but me gently restraining her in that way whilst giving lots of verbal praise worked really well.
She also doesn't like strangers approaching her overhead, so I ask people to hold their hand out and let her approach them before scratching her under the chin, pointing out her hackles and that she is nervous. This approach has allowed her to say hello to multiple people, which she really enjoys.
It might be worth shopping around for a different vet who is more patient and willing to think creatively to help your dog tolerate bring examined. Also hopefully it won't be long before you are able to go in with her.