So about this Texas lawsuit to overturn the 2020 election...
First and foremost, it is important to note that the Texas Attorney General, Ken Paxton, has been under federal indictment on securities fraud since 2015 so this might be a Hail Mary pass to the President for one of those good old presidential pardons before Trump leaves office.

But setting that aside, you might be wondering how can Texas sue another state about how the other state conducted its own election? Let's break this down.
First, states can and do sue each other all the time and while the Constitution allows the Supreme Court to hear those lawsuits directly, it does so rarely. Typically the Court only hears cases where states are arguing about the state regulations of one state that have a negative impact on the natural resources of a neighboring state. Moreover, the Supreme Court has been clear that

"in a suit by a state to prevent other states from enforcing their statutes, the burden upon the plaintiff to establish fully and clearly all essential elements of its case is greater than that generally required to be borne by one seeking an injunction in a suit between private parties" and "application by a state for leave to file a bill to enjoin other states from enforcing their laws will not be granted unless the facts alleged are clearly sufficient to call for a decree in its favor and the threatened injury is clearly shown to be serious and imminent."
Alabama v. Arizona, 281 US 286 (1934).

In plain English, the burden for the Supreme Court to even agree to hear a lawsuit between states is super high. Meaning, if a state has not made its case in the complaint, the Supreme Court will not even bother to take the case. And unfortunately for Texas, it has long been established that states run their own elections. Unless there was legitimate evidence of fraud orchestrated on a nationwide scale, it's highly doubtful the Supreme Court entertains this lawsuit.
Speaking of fraud, Attorney General Paxton was very careful not to allege fraud in this case. The word "fraud" appears 33 times in the 154-page lawsuit, but it's always carefully mentioned in a way that never claims that fraud took place. Instead it says things like "urban areas" (aka Black people) have a "histor[y] of electoral fraud." At one point in the complaint, Paxton flat out admits that no fraud has been found:

"While investigations into allegations of unlawful votes being counted and fraud continue, even the appearance of fraud in a close election would justify exercising the Court’s discretion to grant the motion for leave to file. Regardless, Defendant States’ violations of the Constitution would warrant this Court’s review, even if no election fraud had resulted."

Even if no election fraud had resulted??? Are you kidding me? Invalidate millions of votes, and down ballot races where Republicans won by the way, all on a "hunch" that fraud *might* have occurred where Black people live?
Nice try.
Bottom line here, the Supreme Court will likely hold that Texas has no standing to bring this suit. And if the Court does hear this case, it will only be to set the record straight that Texas has no authority to invalidate an entire presidential election.