What Texas could do is try to split off four additional states, getting ten senators instead of two. Now there’s a nightmare scenario.
DIVISION OF TEXAS. The congressional joint resolution for the annexation of Texas, passed on March 1, 1845, provided that new states, not to exceed four, could be carved out of Texas, the new states to be entitled to admission to the Union, with or without slavery if south of the Missouri Compromise line, and without slavery if north of that line.
While I don’t believe this is still possible, neither is secession and there is no shortage of Texas idiots who want to try that.