Revealing your feelings for someone in a way that won't overwhelm them and thus embarrass either one of you or ruin your friendship is usually a matter of timing and degree. (Bad timing, for example, might be if they're in love with someone else.)
Rather than pour out a total confession of your undying love, use flirting to assess whether the interest is mutual. Take flirting slow and gauge their reactions. My article https://pairedlife.com/dating/Get-Noticed-The-Scie... describes the importance of 1) what you wear, 2) smiling, 3) eye contact, 4) strategic use of interpersonal space, and 5) touch. These are the five critical factors in getting noticed as a potential dating partner.
When you flirt, pay attention to whether your love interest returns your gestures with flirting of their own or if they seem disinterested, confused, and pull away. The more they flirt back, the more you can amp up your charm.
If all signs are go, you can also try various compliments (including compliments about their attractiveness) and attempt to get more alone time with them. If things still look positive for you, you may then start to unfold revelations about how you feel. You can start by saying that you "enjoy" or "appreciate" them (adding specifically what you like ... e.g., they're smart, funny, attractive, we understand one another) and you would like to spend more time with them. They could ask what that means, so be ready to explain a bit. You might ask how they feel about you. This should tell you whether your relationship is staying in the friend zone or venturing further.
Have a goal in mind (e.g., a movie or play together, a joint trip to the park) and suggest that any time they'd like to go/take you, then you'd be interested. If you've read your cues right, you haven't dumped on them all at once, and you'll be able to experiment with dating.