Simply try to browse the page without using mouse, just the tab key. The next step would be to use screen reader, NVDA[1] (Windows) or Apple VoiceOver (MacOS).
There are automated testing tools, but they don't cover the whole spectrum of problems. Nevertheless you can try
* Funkify (Chrome plugin, tries to emulate various disabilities)
* Lighthouse in Chrome Dev Tools also checks some accessibility rules
The full list of things that you need to take care of: https://www.w3.org/TR/WCAG21/ (it's huge I know, it takes 5-7 days to test everything from this list)
Please do the tab test. Some of us do this even if we don't need accessibility tools, as it can be faster (those who create forms which cannot be tabbed through are evil).
* WAVE (Chrome or FF plugin, https://wave.webaim.org/extension/)
* AXE (https://www.deque.com/axe/)
* AChecker (https://achecker.us/checker/index.php)
* Funkify (Chrome plugin, tries to emulate various disabilities)
* Lighthouse in Chrome Dev Tools also checks some accessibility rules
The full list of things that you need to take care of: https://www.w3.org/TR/WCAG21/ (it's huge I know, it takes 5-7 days to test everything from this list)