Business Visas need a local sponsor to support. furthore more info about business visa https://www.konsolosluk.gov.tr/
Enough Funds (US$100 + $50 dollars per day) or a confirmation of reservation in a Tourist Resort or a Hotel
Traveller Health Declaration (THD) must be filled in and submitted online
COVID-19 negative PCR test result, attached while completing Traveler Health Declaration form (sample taken 96 hours prior to departure to Istanbul, counting from the first port of embarkation en-route to the Istanbul).
Number of days : visa issued for Max 30 days , always less than 30 days based on immigration department.