Can a tag start a video call?
It can open the meeting, which is the part that wastes time. Whether the call is joined without a further confirmation depends on the application and on what the platform allows an automation to do silently, and several deliberately refuse. The tag contributes the address and nothing else.
Opening is the useful part
The cost of a scheduled call is not the joining. It is finding the invitation, finding the link inside it, and waiting for the application to decide what to do with it.
A tag holding the address of a meeting removes all of that in one gesture, and it works on any phone with nothing configured.
That alone is worth building, even if a confirmation still appears afterwards.
Joining is a separate question
Whether the application enters the call directly, or opens and waits, is decided by the application and the platform rather than by anything on the tag.
Several meeting applications deliberately stop at a preview, so that nobody arrives in a call with an open microphone by accident. That behaviour is a feature and no automation gets to remove it.
Plan for the confirmation. An automation designed around a confirmation appearing is reliable, and one designed around it never appearing breaks the first time it does.
The recurring meeting case
A meeting whose address is fixed across occurrences is the case where a tag earns its place, because the tag stays correct without maintenance.
A meeting with a new address each time is the case where it does not, since you would be rewriting the tag more often than you attend.
Before writing anything, check whether the invitation address changes between occurrences. That answer decides whether this project is worth ten minutes or none.
A tag at a desk
Put it where the phone lands rather than where it looks tidy, since a tag you have to reach for is one you stop using within a fortnight.
Consider chaining a second step: silence the phone as the call opens, which is the thing everybody forgets and everybody regrets.
And label it. A desk accumulates tags, and an unlabelled one becomes a tag nobody dares tap.
Frequently asked questions
Will the tag join the call automatically?
Often not. Several meeting applications stop at a preview on purpose, so that nobody joins with an open microphone.
Does this work on any phone?
If the tag holds the meeting address, yes. If it triggers a phone automation, only on the phone holding the rule.
What if the meeting address changes each time?
Then a tag is the wrong tool, because you would rewrite it more often than you use it.
Can it silence the phone at the same time?
Yes, as a second step in the same automation. It is the step people wish they had added.