MLB Trade Rumors runs Matt Swartz’s arbitration projections, based off an algorithmic model developed by Swartz, every offseason, and the projections for the 2021 salaries for arbitration-eligible players are now up at MLBTR.
Because of the unusual pandemic-shortened season, Swartz offers up three different projections, based on three different set of assumptions, though I expect v2, which uses what the counting stats would have been extrapolated out to be for each player if a 162 game had been played, rather than just the 60 game season, is probably the most accurate.
The Rangers look to have four arbitration-eligible players, in Joey Gallo, Rafael Montero, Isiah Kiner-Falefa and Danny Santana, all of whom are projected.