Basel III defines capital, leverage, liquidity and net stable funding ratios they're in the form of formulas, and regulations require minimum thresholds to be met I previously wrote about Basel III and its importance in financial markets here โฌ๏ธ https://illya.sh/threads/@1753631798-1.html
banks are also subject to regulations when issuing loans and no - it's not the fractional reserve system in many sovereigns, like the USA the reserve requirements sit at 0% there are other regulatory requirements limiting loan issuance