Webpage I did years ago on the topic, here
That video will take you several hours to slog through, as it's a very boring list of mostly OT verses to show the Bible's style of depicting Trinity. In those days, Youtube was limited to 10.99 minutes, so I had to just make a long boring litany of verses. Which I did, after searching on keywords (sometimes in Hebrew or Greek, not merely English, as the Hebrew and Greek keywords for God are more apt).
So you have to pause the video and look up the verses, sorry. Somewhere I still have that video's creation file, and I can paste the verses in here. When I find it, I'll edit this post to paste the verses.
Of course, anyone can argue over the interpretation of those verses. Have at it. To me the proof of God and hence Trinity should be forensic: LOOK UP AT THE CEILING AND ASK. Then, once you're sure it's the God of the Bible, then read the book and LOOK UP AT THE CEILING AND ASK. For what's the point of reading the book if it's not designed to become a vehicle for Divine Conversation? What's the point of reading Bible, if not to know GOD (and WHICH God, since there are Three).
Now, some will argue that you need human authorities to guide you. Yeah, but so many of them are inept liars, which ones do you pick? LOOK UP AT THE CEILING AND ASK. In other words, THE Authority, aka GOD will know what other authorities HE empowers, and which ones HE authorizes you to learn from. Not, them touting their own horns in the name of 'tradition' or how many degrees they have, since such humans have so often proven to be incompetent liars. GOD FIRST. First Person You Ask, and why would you want to go through any other 'channels'?
But, you have your own conversation, here. I won't dispute you, unless a) you ask me to, and b) you already did your homework on the topic of dispute. For so many of these arguments are centuries old, and long answered.