Put this one in the category of "technically true but misleading and next to meaningless". The headline gives the impression that Republicans in the Texas legislature have introduced a secession bill that will be debated and voted on in their Capitol, which is about as far from reality as you can get.
State GOP conventions typically vote on a slate of resolutions that are written by a Platform Committee in advance of the convention. The committee members are not "politicians" unless they also happen to hold elected office. They're regular folks who have been involved long enough to be elected by local party folks to spend lots of time going to meetings. These resolutions are then voted on by state delegates, who are also just regular folks who take their own time to be involved with the GOP and go to a series of meetings where local Republicans decide who among them should get to vote on things at the state convention.
The big thing that state delegates will vote on this year is delegates to the national convention. (Obviously that was a bigger deal when a contested convention seemed likely.) But they also vote on these proposed resolutions, and have the opportunity to propose their own resolutions from the convention floor. If such a resolution gets the votes of a majority of state delegates, it...becomes a passed resolution, with exactly zero authority over any elected official. I assume this resolution won't pass at Texas' state GOP convention. But if it does, no GOP lawmaker will be obligated to introduce or vote for such legislation (and any lawmaker who wanted to secede could introduce legislation without needing any convention resolution).