The following is mentioned on every visa application page on the gov.uk website as far as I know, specifically if you are applying from inside the UK.
You must not travel outside of the UK, Ireland, the Channel Islands or the Isle of Man until you get a decision. Your application will be withdrawn if you do.
I can travel outside the UK on my graduate visa and enter the UK again but my visa application for Global Talent Stage 2 would be withdrawn according to the wording on the Global Talent Visa page.