President Trump: "If the House will not agree to that adjournment, I will exercise my Constitutional authority to adjourn both chambers of Congress. The current practice of leaving town while conducting phony proforma sessions is a dereliction of duty."
Note: Obama made Recess Appointments in 2012, despite Pro Forma Sessions, claiming the Senate was "not really open"
In 2014, the Supreme Court ruled against him in a 9-0 decision, noting “The Senate is in session when it says it is." https://www.washingtonpost.com/politics/supreme-court-rebukes-obama-on-recess-appointments/2014/06/26/e5e4fefa-e831-11e3-a86b-362fd5443d19_story.html?noredirect
In 2014, the Supreme Court ruled against him in a 9-0 decision, noting “The Senate is in session when it says it is." https://www.washingtonpost.com/politics/supreme-court-rebukes-obama-on-recess-appointments/2014/06/26/e5e4fefa-e831-11e3-a86b-362fd5443d19_story.html?noredirect
As I understand this, if the House refused but the Senate moved to adjourn, President Trump could proceed.
"in Case of Disagreement between them, with Respect to the Time of Adjournment, he may adjourn them to such Time as he shall think proper"