Operating downhole wellbore valves

A method of operating a downhole valve, comprising:

• running an autonomous downhole tool into a wellbore tubular that extends through a wellbore formed from a terranean surface into a subterranean formation, the autonomous downhole tool comprising:
• a housing comprising one or more modular sleeves that ride on the housing;
• and
• an autonomous carrier coupled with the housing and comprising an actuator module;
• moving the autonomous downhole tool to a particular location in the wellbore tubular at which a downhole valve is installed;
• adjusting a first modular sleeve of the one or more modular sleeves to expose a shift latch, the shift latch comprising a latch profile shaped to interface with a shift sleeve profile of a shift sleeve of the downhole valve;
• engaging the latch profile of the shift latch with the shift sleeve profile of the shift sleeve;
• generating a shift force to adjust the shift sleeve on the downhole valve with the shift latch engaged with the shift sleeve;
• adjusting a second modular sleeve of the one or more modular sleeves to expose a tubing seal from the housing;
• and
• engaging the wellbore tubular with the tubing seal to maintain the housing at a stationary location in the wellbore.