How do I get into a masters course in pure mathematics? My question is as stated in the title and to elaborate more:

I would like to know if there are any standardized international exams to enter a masters course in pure mathematics (besides GRE Math) and available for a scholarship simultaneously? (I'm a graduate in Automotive engineering, 23 years old and don't have a math degree yet).

I have completed 5 courses related to engineering mathematics during my tenure as a engineer.

I've been prepping only on math (topology, differential geometry, advanced calculus, real analysis, etc.) for the past 6 months and am almost ready for an entrance exam.

Can anyone offer me alternate options or solutions on how to go about this?
There are no standardized international exams for mathematics. Strategies for applying for a masters in Maths is no different from any other program. The best, and possibly easiest, way to enhance your chances for acceptance is to find a means to self fund. Specifics on how to tailor an application are very country and program dependent.